Even if a cat is scared of being stuck in a tree, sometimes being approached by a stranger scares the cat more, and it climbs beyond human reach...
Happened to me once, while I lived in the city. I got about forty feet up, the cat moved fifty feet up, and the fire department had only a forty-foot ladder, and the firemen were bigger than I was and obviously couldn't have climbed higher even if that had been their policy. So we used a different strategy. One person climbed about thirty feet up holding a tuna sandwich, and the other aimed the garden hose at the cat, to help her remember how to climb down trees. She remembered, all right, and she decided she liked people who shared their tuna sandwiches, and that was how my group house acquired our Patchy Cat.
Of course, a truly feral cat might have stayed in the tree until it fell out and was injured...you never can tell.