I admit to not having known anyone since the transistor radio days, or when cars came with a single, dash mounted speaker that would prefer to listen to a single speaker.
Is this a thing? Mono listening, I mean? If so, why? I am curious. I built a Bluetooth box (it also had a cd player) for my son with a car stereo and a desktop pc power supply. Mounted a 10" MTX woofer and a couple coaxial car speakers all in the same box. Although it wasn't mono, all the speakers mounted so close together almost gave it mono performance, depending where it was located or how close or far away from it you were. Thing actually sounded pretty righteous for what it was.