I think you’re overestimating the average quality of English as a second/third language education. The internet continuously becomes more accessible across the globe, which has overlap with lower quality and lower frequency of English lessons. There’s more exposure from speakers that don’t use the same native alphabet as well, so use is not so universal. When speaking is the primary use of language, reading is secondary, and writing is tertiary, mistakes get interesting. It’s not too hard to hear the word “extreme” but visualize the spelling from words like dream, team, cream, or beam, all words I could see being more commonly used than extreme. It’s easier to learn “very” as a modifier to a common adjective.

Source: I work in the US with mixed central/south American-born employees and travel to Mexico often. I see casual US-sourced mistakes, of course, as well as those distinctly from Spanish-speaking writers. My Spanish is just as incorrect. If you can say it out loud and still make sense, I’ll vote for non-native English speakers every time as the cause