If you go to Basel, Switzerland, you'll find that the German they speak is not like the Stage German that Americans are taught, nor like the German spoken in Bavaria. Cajun French is not like the French spoken in France. And Latin American Spanish is not like the Spanish spoken in Spain.
Isn't it wonderful?
I have never been fortunate enough to make it to Europe or the UK, though I have always wanted to go. I have been to Mexico quite a few times. We met some people from Brasil when we were in Cancun one time, and of course they spoke Portuguese, but it's not the same Portuguese as is spoken in Portugal. In fact, they didn't speak English, we don't speak Portuguese, so we communicated with them in Spanish and French, LOL. And the Spanish speaking South American countries their Spanish is much different from Spain or Mexico.
That's only to be expected that languages will evolve that way.
English, Latin, and Mandarin are languages that are more universal than most. I know a lot of Latin from my medical transcription training. I suppose I should try to learn Mandarin but I hear it's very hard. When I was very young we lived in Okinawa, Japan, and apparently I spoke Japanese fairly well though I don't remember much, maybe a few words but I could not have a full conversation with anyone (we were there for 3 years and we had a maid and a sewing lady who used to dote on me and cook for me). Mom said I used to eat some very strange foods that no one else in the family would touch, LOL.
Edited to add that my uncle from SE Texas (near the Louisiana border) was Cajun. He spoke good English (he was married to my mother's little sister) but many people in his family barely spoke a word. And you certainly are right about it being vastly different from French in France. Interestingly, many Cajuns in Louisiana settled there after leaving Canada. They came down the Mississippi River (trappers and traders). My uncle Buster came from a long line of riverboat captains and was indeed a boat captain himself.
Okay, sorry for going so far off topic!