Per the original question, I think it just narrows down to corruption of the language on both sides of the ocean, and in this case, I don't see a reason to get worked up over it.
The US:Sport = one specific activity. (basketball, baseball, golf, etc.)
Sports = multiple athletic or competitive activities.
The UK:Sport = apparently serves both US definitions, and it's up to the user to figure out based on context?
The US:Math = The short form of the word mathematics.
The UK:Maths = Same definition.
The US:Final (referencing aviation) = i.e. "The aircraft is on final (approach)."
Also recognized by the FAA as the proper wording.
The UK:Finals = i.e. "The aircraft is on finals (approach)."
I personally can't figure this one out, since I have yet to see an official aviation document for the UK or any European country recognizing the "s" on the end.

It's not something we can change since people are set in their ways, so I guess we'll just have to get used to it as various regions around the world communicate with each other more and more.
