Well why do the Brits call an elevator a "lift", cigarettes = fags, apartment = flat, french fries = chips, garbage can = dustbin, lawyer - barrister, etc.
Lift, because it lift things up.
Fags, I honestly haven't a clue :dunno:
Flat, because that is what it is. All on the same level. Where as a apartment can have a upstairs level too.
Chips, because they are chipped out of a potato.
Dustbin, is because that is what it is for, dust and other rubbish. Which goes into a bin.
Actually we have solicitors and barristers. The barrister is the case expert that fights a case in the crown court or above. But not in a magistrates court or below. As a solicitor will fight your case there.
Now I've answered your questions. How about I reverse them and ask you why you call them what you Americans do?
Here another question for you then. What is English? As the language is never used anymore as the queens English and there are many accents and variations.