> Some radio stations manage to put ads on the 14-segment display that is supposed to show the station name and/or frequency.
We can talk about hardware protection against ads. The hardware would need to recognize allowed data - like station name and frequency - and reject disallowed, like attempts to make a running text. This will limit functionality; maybe it's worth it.
We can talk about software protection - when user controls some layer of software. We can implement it as a type system, with the same result (only now we can modify the software layer if we need). Type system which makes ads non-representable looks like a nice solution.
Guilty myself in writing a game resembling Tetris on a 8-segment display (blocks moving horizontally), so yes, people can be inventive...
And if it doesn't, there is always room for a sticker. Buy a new laptop and you are going to see half a dozen ads before you even turn it on: on the box, on leaflets inside the box, and in the form of stickers,... It seems that only Apple doesn't play that game, but the privilege is expensive.