Haha, what an awesome way to get new neighbors. Simply outlive the old!
Young, inexperienced cats, cats that take the defensive instinct to get to a high place too far (ie. an extremely frightened cat, such as one treed by dogs as the OP suggested), and cats that get their collars stuck are probably the most common ones to get into a situation in a tree that they can't get back out of on their own. You are more likely to find dead cats just under the tree who fell from weakness, but you will find them stuck in trees too (the morbidly curious can do their own googling for that one
). Even for the cats who do get down, those who fall can still end up dead or needing serious vet care, or can require treatment for sever dehydration (a problem in and of itself, especially in individuals who are prone to UTIs and kidney issues). So even if the cat gets down, the owner may very well find out that they wish they had not waited.
Cats are built well for climbing...up. They have powerful hind legs to climb with, and hooked claws to grapple with. One of the reasons getting back down can be too hard for them, is because most try to go head first (clouded leopards, Fluffy ain't). Those hooked claws suddenly can't get a grip in that direction and skid instead. That alone can keep a cat from trying again. Some do figure out how to climb back down butt first, but some will not feel comfortable enough largely due to their weaker front limbs.
Also, it really isn't a matter of waiting for a cat to get hungry enough to climb back down. Some will respond to food if comfortable enough and early on. Once you get past a certain point of dehydration though, food is the least of your worries. Mammals can loose much, much more body weight from lack of food than they can from lack of water before they perish. Most severely dehydrated animals will not eat even if abundent food is before them (I've seen this way too often with mice who have a stuck bottle. They weren't getting water, and stop eating, but people mistake the not eating part as the problem, and give them more food. Then they die.). A truly stuck cat can be both very thirsty and hungry, but that doesn't mean they'll be coming down the trunk anytime soon. It is a very slow and distressing way to die (I know many people in developed countries have not experienced the deep confusion that comes from lack of water...it can make situations even harder to get out of), which is why it is so awesome that this treed cat was retrieved before things got even more serious.
