Of course keyboards can be relabeled. But they usually aren't. If, hypothetically, keyboards came with knowledge of their original labeling, that would be meaningful information. If computers used it to set a default key layout, that would make for a better default if the goal is to make key behavior match the labeling. It would fail to match the labeling if you changed the labeling, but it would still be accurate much more often than the current default.
That said, I question whether most people actually want key behavior to match the labeling. I think any touch typist would rather use their preferred layout regardless of labeling.
As a recovering Dvorak user, I would very much like the match-the-legends behavior, because for quite a long time I used a keymap which was not the default. At one job I had an Advantage2 that I carried around with me because the keys were internally remapped (when you pressed a key it reported the scancode for that letter on QWERTY) because of how time consuming it is to add a keyboard layout in most operating systems. Unfortunately that kind of internal remapping is mostly only found in some very expensive keyboards. There's at least one vendor that sells a USB dongle that does the same remapping to a pass-through USB keyboard for the same reason.
This problem would be infrequently encountered in the US (mostly just Dvorak and Colemak addicts) but is a lot more common in Europe due to AZERTY.
That said, I question whether most people actually want key behavior to match the labeling. I think any touch typist would rather use their preferred layout regardless of labeling.