I think everyone would've learned a lesson the hard way. Both resulting in injury to themselves, and unfortunately injury or death to an animal.
When I bought my first set of Varanus tristis, I learned very quickly they were not as amenable to handling as the other monitors I kept at the time, and they are in fact really good biters!
Another husbandry lesson I learned was that an open-topped pit with 1.5m high fencing is not always enough to keep Lace Monitors in. I'd kept a large male in such a pit for months before getting the chance to purchase a Bells Phase breeding female. She did not like to stay put, whereas the male was a lot more laid back. I discovered one day that she was nowhere to be seen, only to find her hours later wedged down the gaps in a bessa block retaining wall of my next door neighbour. She was not happy to come out. But it taught me a lot of things (and cost me a bit of cash to put an aviary style top over the pit).
The hardest lesson I learned was that such an aviary top will not stop thieves from getting to an animal if they want it. Trust is a big issue for me in the herp game, and I sold my entire collection not long after that theft, partly because of the theft.