Many cars have daytime running lights that are almost as bright as headlights. Out here in the desert there are or used to be mandatory headlight zones on some highways because of heat haze/mirage. Cars also have better charging systems so running with your lights on is no big deal for the electrical system.

The ones that really frost me are those running with their foglights on at night when there is no fog. Mind you, some of the blame lies with the dumb DoT requirements (or lack thereof) regarding headlights. Folk run the fogs to get some sprad and foreground light while on low beams. Coming from Europe I was appalled at the awful lights on US built cars in the late 90s. No wonder you all ended up needing airbags, nobody could see anything at night.