Sure, but that’s orthogonal to laws and their effect on behavior. People ride with headphones, dangerous or not, legal or not. I’ll was honestly asking what difference a law makes when people obviously do it, and in areas where I’m sure it’s illegal. Hell, I’ll see people driving with a headphone in each ear, and I know for a fact that’s illegal in at least three states.

In-ear headphones can surprisingly improve spatial awareness by reducing the wind noise at certain speeds.

That assumes they are not playing anything though.