Some cars in traffic wont move and others will

When i spawn traffic its a guessing game that it spawns a car that will move because sometimes it spawns in a car that wont move in traffic and have warning lights on stopped in the middle of the road and i didnt hit it. This happens on every map
here's a example (idk if im doing the pic right)
This mostly happens on some mod cars or at times a regular car.

Any help?