I’m not justifying it - just explaining why it happens. If you walk into a male-dominated space and start lecturing people about gender pronouns, this is the reaction you’re going to get. If they’d stuck to talking about cars, it wouldn’t have happened in the first place.
It’s also worth noting that some languages don’t have gendered pronouns at all - Finnish, for example. We use the same pronoun for men and women, so when I say “he” in English, I might be referring to a man or just a person in general. I know that’s not grammatically correct in English, but for me - and probably for a lot of others - “he” doesn’t automatically mean male. It’s just how the pronoun from our native language maps over.