It's not really because everyone learns at school. And in fact it only takes a few years (my kids are going through it now and I was surprised at how quickly they went from not being able to read at all, to having better handwriting than me).
It's like, learning a language is really hard. Learning your native language is super easy, barely an inconvenience.
So I think I would be more accepting if he said "sorry I can't speak English because it's a second language so I used AI to help", but he didn't.