We suggest that you look for members of a body called APTAE, which basically translates as Peruvian association of adventure and eco-tourism operators. As a body for years they have been pushing for the authorities to introduce some form of legislation to govern who can and cannot operate certain activities, and above all to raise safety standards. A couple of years ago after a bunch of fatal rafting accidents - almost all involving Israeli backpackers- a scheme to licence rafting operators was introduced. Unfortunately, the scheme was not strict enough- some operators who should never have been licensed were approved, which denigrates the whole thing a bit. But at least it was a step in the right direction.
There is absolutely no legal framework whatsoever for any adventure activity in Cusco apart from the rafting that I just mentioned which is currently stalled, and for the Inca Trail trek which is heavily regulated- but no other treks and no other activities. That is not to say there are no operators here who are safe, there are, a few who looked outwards, to other countries for the standards to meet and looked inwards to make sure they are really meeting appropriate standards that would be expected in Europe and the US. Our operators do that and are members of APTAE.
I mention the Israeli backpacker rafting accidents because they illustrate a large part of the problem- a lot of people expect to get something for next to nothing. These backpackers were paying about 60 dollars for a 3-day Apurimac rafting trip- they drove the price down. And sadly there were, and still are, companies willing to cost cut enough to meet those kinds of prices. How do these companies meet those prices? By cutting corners and cutting safety- they use inexperienced guides who are willing to pretty much work for free to gain experience ( on a class IV river!), they reduce the number of guides, reduce the number of safety kayakers, squeeze more people into the rafts than is safe, use lifejackets that are long past their service date and thus have greatly reduced flotation, because renewing equipment costs a lot of money, use cheap buses that are cheap because they are not spending on maintenance, and much more. Those companies made a lot of money by agreeing to the ridiculously low prices that that particular market was demanding- and as there were lots of these backpackers, overall they made a lot of money- but with a lot of near misses along the way, and quite a number of serious accidents and various deaths. That whole industry died when 3 deaths in a few months led the Israeli foreign office to ban its citizens from rafting the Apurimac. The river which once saw hundreds of rafters each week, now sees far fewer.
I remember, before the new Inca Trail regulations were initiated, companies were selling really cheap Inca Trail treks. Our main trekking operator said that was because those companies required a minimum of 20 people, they fed the trekkers just ramen for every meal and they used old equipment. Sometimes our operator would loan tents to some of those trekkers when it was raining because the tents that the other company gave them had holes in them and they were getting soaked - that's bad when it's cold too.
Rainbow Mountain is another disaster area- people have died due to inexperienced guides taking people who should never have been there, up to 5200 metres far too rapidly. The authorities closed the mountain a month or so ago until the weather improved after a few incidents where they had to go and rescue groups that had got stuck up there in the snow. Groups that should never have been up there at that time due to the high risk of inclement weather. Once again, it was cheap! People wanted cheap trips and so they got companies willing to risk safety in order to meet the prices they were demanding. Inexperienced guides, and companies that do not really understand adventure, understand the mountains, make bad decisions. Those groups should never have been up there in that weather.
Zip lines- again people pay cheap- the one that killed two people last week ( which is what started this whole commotion to suspend activities) was made out of wood. There have been many zip lines in Cusco over the years, almost all of them have killed people. I'm told there is only one ( the one connected with the Skylodge) that has not - every other one has killed people and that includes the one at Santa Teresa. The Maras one also killed someone in January, yet it was still operating, allowing it to kill two more last week. But it was cheap.
Everything has a price, if you are not willing to pay that price upfront, it has to be paid for somewhere along the line, by someone. If you get away with it, then those you are lucky, but there are people behind the scenes who will have paid for it for you- underpaid staff- the children of those staff who cannot afford the extra to go to a decent school, because their parents are out all day working to earn a pittance. A tired driver who later has an accident on another job, because he has to squeeze in more hours than he should to make ends meet, because you and the cheap company you chose are not willing to pay the real price of his services. You may have read horror stories about some companies offering cheap group tours at Uyuni Salt Flats in Bolivia. They use overworked drivers using under-maintained vans, no English-speaking guides and bare-bone hostels.
The problem is too many people cannot see past the dollar sign, not the clients signing up for cheap services, nor the companies willing to take their money. I remember years ago when I was in Ecuador, looking for a bargain climbing trip myself. I found one at a really good price, but the night before I was supposed to start, the company called and said they had to cancel the trip because my guide froze to death on one of the mountains. Gee, that's not very good for business! I'm sure he was not very experienced or prepared.
It is important to note adventure does carry an inherent risk, sometimes an accident, even a death will happen that is not anyone´s fault. You can never fully eliminate risk, if you could it would not be adventure. But you can learn to reduce that risk. For instance, it is not someone´s fault every time a skier is swept away in an avalanche and dies. It is not always someone´s fault if someone falls off their bike and fractures their wrist. A guide and a company cannot be the only people expected to work to control the risk, clients themselves need to be aware so they too can play their part in looking after their safety.
Several other countries have associations for adventure and ecotourism tour operators who agree to maintain quality practices and procedures that include safety measures. For instance there is ABETA in Brazil and ASEC in Ecuador. I think that members of organizations like these are going to be reliable and trustworthy companies, rather than companies who are desperate for business and are offering bargains too good to be true. I know that in Brazil, the government has tried to get rid of the guys at the Manaus airport that would wait outside and offer people cheap Amazon trips, but would not offer anything close to what they promised.