Huh. I never understood the terminology "radio button", and I have no memory of noticing such a thing in a car. But it could easily have been there; why would I have cared?

I did have a tape player with buttons (play / rewind / stop / etc) that, when pushed, unpushed the other buttons. So I have a mental model for buttons of that kind. But I've never associated them with a radio.

Also, I've never associated the radio selector HTML element with a button (HTML or otherwise). Buttons are about triggering effects. But radio selectors are about selecting something; they have more in common with checkboxes.