Because, even though I'm a native English speaker, I can't fckn understand half of what people are saying either because of ascents, other noise, not understanding context, and generally having a hard time correctly decoding speech unless it's the only thing happening. Maybe it's a symptom of some sort of non-neuro-typical trait.

Also, I've always had a tendancy to hear egg corns where most people hear the correct words.

https://en.m.wikipedia.org/wiki/Eggcorn