The point is to present a solution and give them the chance to just say "GO" or "Woah" instead of handing them a problem with the expectation to work through it with you.
Moreover, the point of just notifying the "UOD, ..." is to minimize getting entangled in the bureaucracy. Calls can often lead to either massive time-wasting for everyone in playing phone-tag, or escalation and further pointless delay which literally benefits no one.
Distracting other people from their tasks to get a definitive answer on an item where it is reasonable for me/you to make an executive decision and give them an opportunity to check it before implementing it is really most often best for everyone.
Now obviously, if it is a real unknown on a critical item where getting it wrong will really fork-up someone's week, then you call and nail down a hard answer and then document it in writing.
But, the point is that for a surprisingly large amount of stuff, "UOD, ..." works amazingly well for everyone — and I do mean everyone.
YUP. I first heard of it as "UOD" = "Unless Otherwise Directed".
Extremely useful, as in politely explain the basic reasoning and "UOD, I'll be implementing X, Y,, and Z starting Thursday..." make sure everyone gets that message and proceed. Works both within organizations and even with partners and customers. I also can't say I've ever heard a complaint when it was used.