I’ve been seeing this a lot lately and saw it twice on my way home from work last night, once on an expressway. It seems to always be newish SUVs from US manufacturers. The cars are driving at night with headlights and even fog lights on (with no fog in sight) but no tail lights! They are completely blacked out from the rear which seems really dangerous. I understand that this is just a case of idiot drivers but why would any manufacturer enable this practice by allowing such a light setting for any vehicle? Are they trying to improve gas mileage by eliminating the power drain required to light up the tail lights???
As others said, most car have front “daytime running lights” (active even when the light switch is off, and just barely bright enough to look like headlights from an oblivious driver’s point of view). So, that is why people drive around with their lights off. They think they are on and/or oblivious and/or drunk and/or high and/or just forgetful.