When the W3C first decided to be a part of HTML5, they did that, yes. Initially both specifications were identical.
They've been diverging ever since though, and the forms section is it seems still being worked on. Especially the more problematic inputs like colour.
What is infuriating however is the way that Chrome/Chromium insists on adding commas to numbers, so my order number 123456 becomes 123,456 to the user. Not a massive problem because submitting it will submit 123456 but nevertheless, I don't want it to display that way.
Yeah, imagine your user is Dutch and they think that's 123.456 (one hundred twenty three wholes and four hundred fifty six thousandths). A dangerous assumption on the part of the browser. (Over here, 50 euros is displayed as €50,00 or €50,- so the decimal-comma problem is... a problem)
Likewise, I can't do any locale overrides for the date types, so I'm forced to have the YYYY-MM-DD format, which is not always what I need the user to enter.
Don't forget month and week types if you can get away with them.
Supposedly, the users' locale settings are supposed to adjust. So Americans whose system claims it's in the US would allow MM-DD-YYYY while most others could get DD-MM-YYYY or whatever. Or, I remember Bruce Lawson and some others discussing this and supposedly that's how it's supposed to work.
The browsers are also supposed to be able to choose their own presentation of dates. While I don't dislike Opera's, I can't imagine everyone wanting a jQuery-style date picker for every date. Similarly we haven't moved over to type=date because we're still using the back-ender's wish of three separate select dropdowns. Was easier on his end for validation I think, not sure.