I'm mid-thirties and was recently asked to teach a 50 yo best practices for development in Node. And not like Node specific patterns, but more like how to handle http requests. I'm pretty sure that guy is way above my skill set - he's smart and he has 15 years of work experience on me. I turned the offer down since I would have looked like a fool, like a kid teaching an adult how to drive.
The age bias is real.