There is a standard for this. If you google HTML5 autocomplete attribute you’ll notice all the possible autocomplete attributes and those cover pretty much just about anything. To my knowledge, the major browsers implement nearly all of them.

What’s preventing this from happening? Nothing, clearly, devs just don’t implement it because they don’t know about it, and they don’t know about it because they’re busy learning about or implementing something else. How would you universally communicate to everybody that this is now a thing? How long will it take you to fix 90% of the forms out there that were set-and-forget five years ago?

Besides, for most it’s easier to use oauth with google or whatever and automatically get the name and birthdate from there (of course, often enough, they have the non completed form anyway…)