[soni96pl]

UUID is used where checking is difficult, think distributed devices offline at a plantation. How could checking be easier in that case? It would require infrastructure that doesn't exist. There are many other cases where it's easier to handle collisions.

[erikerikson]

Agreed. While it's an uncommon scenario it is a significant case and UUID shouldn't be used in that case because as you write checking doesn't work well. Better to use an alternative such as coordinate/reserve monotonic producer IDs that get paired with monotonic, per-producer monotonic sequence IDs to produce guaranteed unique, well-ordered IDs.

[edit: in IOT it's common to issue x509 certificates as a type of authentication which could be used instead of using producer IDs. Solutions always have to be paired to use case.]