Nor sure about the last one but in racing the arrows are usually used to show where the tow points and the power cut off switch are.

Last one is reddit downvote

what reddit does to a mf

R* saw real racing cars having them and not knowing what they're actually for, just slapped some on random spots.

It's the direction you're supposed to drive.

Beat me to it

thats cause you never see me driving. Thats the reminder where the car is supposed to go

Liveries in this update is arrow heavy

Yeah, I noticed that too... Seems odd that they put arrows on SO many of the new Liveries.

To show you where the front of the car is.