No, it's due to the ovewhelming exposure to media from the U.S., mere spellcheckers oughtn't interfere with 'underground' vs 'subway', 'film' vs 'movie', 'flat'

No, it's due to the ovewhelming exposure to media from the U.S., mere spellcheckers oughtn't interfere with 'underground' vs 'subway', 'film' vs 'movie', 'flat' vs 'apartment', and so on and so forth.