Traffic lights (also known as stoplights) are meant to be on 24/7 in this game. How else would you know when you're allowed to go or when the AI will ram you?
Headlights might be a bug but it might also simply be how they're modded, as erbkaiser mentions is the law in a lot of countries now.

Modded trailers are added into the pool of trailers to be spawned, alongside vanilla SCS trailers and any other modded trailers. Only when a mod specifically mentions it replaces specific trailers, will it remove whatever it replaces from that hidden list. AFAIK all of Jazzycat's stuff is additive, ...

Yo, thanks!