Even the oldest CRT televisions have a "brightness" control, and it's supposed to be used to set the black level to black, not grey. The face of the tube has a grey color while it's off because that's how the surface of the tube looks - but that's not the result of emission from the tube, and even by the eighties tubes had dark anti-glare tinting for this. Unless you're shining a light on the tube, the black levels should be black.

Are we to say that the black level of an OLED display isn't black because external light can raise it through reflection?