It’s comical how many are trying to defend an ignorant sounding idiom like “How come”. Americans are known for shortening words, ’couldn’t, can’t, wouldn’t, etc. etc. etc.’ so it’s rather strange that this is one case where a perfectly good word like ‘Why’ is extended into ‘How come’. Makes no sense to me in a wider sense. Back in the ’80’s it was rare to see it printed and rare to hear anyone use it. Now, it’s everywhere. Yes, I’m aware language needs to change and adapt, but this? Wow. Websters says it’s rather exclusive to the US.
HA!