Your computer doesn't actually know what the keys for WASD are. It just receives a number (commonly called scan code) for the pressed key from the keyboard, and has to use the mapping to determine which key that actually was.

There's some convention for which scan code to use for which physical position on a keyboard, but that's not correlated with what's actually printed on the key caps. E.g. on common QWERTY keyboards the "A" key will have scan code 4, but on AZERTY keyboards it will have scan code 20.

Games can probably get away by listening for the scan codes of the keys in the position commonly used by WASD, but it's a bit fragile, and they can't actually tell you what's printed on the keys they're listening to. The lack of consistenency is certainly annoying, though...