There have historically been white (compulsory) bus stops and red
(request) bus stops in London. There still are. Children are taught

At a white stop, you shouldn't need to. That's not laziness.

I've always felt if you want to get on the bus then it's no harm putting
your arm up to stop it, it's only a few calories effort and it's never
failed me yet.

However if buses no longer stop at compulsory stops then they should change
all the signs to red to avoid confusion.

D