Pans that aren't non-stick can be made far less sticky by not adding anything (except maybe some fat—oil, grease, lard, butter [ghee especially], et c.) until after they're hot. I think it causes phase-changing water in whatever you added to kind of push the food off the pan. You can see this in action by dripping water onto the pan—when it's hot enough, the water will ball up and kinda dance on the pan, while lightly sizzling (that's the lowest point at which it's OK to add food and it probably won't stick much—hotter and the water will sizzle aggressively and may evaporate too fast to really evaluate its behavior, of course, and for most purposes this is too hot to add food anyway, as it'll instantly burn the parts that touch first)

This makes very low-temp or delicate cooking in non-teflon pans a lot tougher, of course. Or anything for which starting from a low temp and slowly increasing is a nice thing to be able to do (tempering chocolate, for example)

[EDIT] Basically the value prop of teflon pans is that they can do just about everything at least well-enough (if not always being the best possible option) with just one type of pan, and that they are much more forgiving of lazy/untrained use or mistakes than stainless or cast iron. They can't do much that's impossible elsewhere, but it may require better technique and closer attention, and maybe having multiple types of pan, if you don't have a teflon option available. The above is one of the ways in which you have to apply some extra care and technique to avoid bad results, which can be all but totally ignored if you're using (undamaged) teflon.

Their main down-side (any health concerns aside) is that they are easily damaged by hard tools. With stainless and cast iron you can scramble your eggs with a metal fork, in a pinch, and it'll probably be entirely fine. Do that in teflon and you'll ruin the finish before long.