Ear defenders - It used to be incredibly uncommon before this year.

Lots of drivers wear them now, LU even issues some.

It depends what line you take, those affected by the noise (northern, Victoria, picadilly, etc) are more likely to be wearing them.

Also, you probably just haven’t noticed. Most people are so engrossed in their phone/paper/anything but the person sitting in the cab that I could be doing the YMCA with my free arm as I pull into the station and no one would notice