UUIDs and hashes are not the same. For example, hashes are often taken over untrusted data, which could be manipulated to produce a collision. UUIDs aren't me

UUIDs and hashes are not the same. For example, hashes are often taken over untrusted data, which could be manipulated to produce a collision. UUIDs aren't meant to protect against that. I'm sure RoR just did the straightforward thing, didn't get cute, and called it a day.