I've lived in enough states that various parts of my experience from various jurisdictions both confirm and refute each of the points made.
It's important for everyone to remember that their experience is not the only experience.
In all 50 states, plates represent the registered owner and not the driver, because non-owners can drive cars in all 50 states.
As for safety and emissions, only a minority of states do each of these, and the majority of those denote compliance with a sticker, or have exemptions:
https://en.m.wikipedia.org/wiki/Vehicle_inspection_in_the_Un...
There is no other indication on the license plate. just the numbers and letters.
I assume that expiry dates on US plates is related to either road tax or vehicle inspection
Usually yearly registration, though some US states do gate the registration completion on some forms of inspection.
California, for example, requires emissions testing every other year for cars older than a certain age, and won't send the new registration until that's been completed. But most states don't require any kind of regular safety or general road-worthiness inspections. I think that's kinda bonkers, but I haven't really looked at stats around how many car crashes are caused by a failure to maintain a car or its safety features. It's possible that the cost of doing such testing is often deemed too high, when considering the benefit.