Terminologies

I find it ridiculous that people in the western countries whose first language is English (or so they claim) do not understand phrases which are not used locally by them, but mean the same, and I am not talking of slangs or some very complicated words. Something as simple as hire and rent or even petrol and gas. I dont think it takes too much effort to understand such words. Is this arrogance/narrow minded-ness or blissful ignorance?