[bilky asko]

For example, EMid and WM are easier to tell apart than EM and WM.

Not if you can read, and that's what you're looking for on Freesat.  On Sky/Freesat it's irrelevant, as you'll get the correct region anyway on 101.

If you're scanning for some other region, then quite honestly EM couldn't mean anything else in the UK. To say otherwise is somewhat ridiculous.

I can tell the difference between SW, NE, WM, EM, SE, NW . . . I doubt there are many people who can't.

That's the point - as a viewer you are most likely to only ever see your region, so there's no need to enforce a consistency to appease the nerdy few - especially if there's a use in making them more visually different as names for internal reasons, perhaps.