I don't really see the point of UUID. I know the probability of a collision is effectively nil, but effectively nil is not even close to impossible.

Can somebody give an example where you have no choice but to use UUID? From all the uses I've seen, I can see an alternative design without UUID. Sure the design might be slightly more complicated, but at least it doesn't have a non-zero probability of failure.

UUID smells like global variables to me. There are many ways global variables make for simpler design, but its just lazy design.