On the other hand, years ago one of my indoor cats escaped and climbed onto the roof and just sat there mournfully crying until we figured out where he was and got him down. Heck, the indoor cat I have now got herself stuck on the side of a not-steep hill because the ground cover was too loose and I had to climb up and get her.
I think it's just life experience, and indoor cats aren't the examples to judge the species by... any more than the avg sedentary human is when compared to people who actually exercise as much as we're all supposed to. ;)
Smart apex predators rapidly lead to worldwide extinction events.
Took about 20 hours before she came down. Just before the tree surgeon was arriving to help get her down.
Edited to add: or you could just leave your actual ladder in place. All three of my cats have learned to climb a human ladder (albeit only a short one, with 5 steps) - both up and down