As a guess, I would bet that the legal requirement is that it be manufactured in such a way, not that the car's operator keep it connected to the telephone network after purchase. I shall research and find out!
It's internal to the vehicle, so I doubt it would stand out visually. The ALPR stuff and mobile towers aren't (yet) integrated.
It's a legal requirement to have it. Sure, I can rip out the head-lights too, but then I am not allowed to use the car any longer on public roads. If emergency call is part of the cars registration I am probably not allowed to disable it without voiding the registration.
As well, no one does this. If you do it, you stand out like a sore thumb.