That works when you want to create something new. If you want to simulate then, by definition, you imitate real world features. I don't care about real cars, real tracks, etc - but putting forward the safety hazards as an example like you did left it open to debate as to what features (graphical or otherwise) that are already incorporated into LFS would be necessary.
Personally "sirens", strobes and cherry tops are not what I'd care to see. If some league wants to implement a safety car feature it's up to them to do it - just use a skin that stands out and you're set.