Such is the police culture in America. Realistically, you can never have enough backup on a traffic stop. Additionally, traffic stops are up there with the most dangerous activities that an Officer or a Deputy can commit to. From being shot, ambushed or ran over — the risks are high and backup can never be amiss. Yes, even if you're fully compliant. What if it's all a play? It's happened before, and it has happened in real life. Additionally — caution is heavily exercised at traffic stops, and it's what people are realistically taught at the academy.
However, police officers in America have legal rights to ask you to step out of the vehicle.
This is covered in the Pennsylvania v. Mimms caselaw. You can read about it here. Officer safety takes greater priority than the individual's comfort. When my character feels particularly unsafe at a traffic stop, they may very well ask somebody to step out of the vehicle and talk to them at level, on the sidewalk or someplace else. They can also do a pat-down for weapons.
It's less about people wanting to jump to action over a white girl being pulled over in Hawick, it's more about people responding to assistance requests broadcasted over the radio. You can also approach traffic stops on your very own without any backup if you so desire. That is entirely up to you, but backup is never, ever amiss.
If someone has to be forced out of a vehicle, as you say, that means they are not compliant. I'm going to pass that up as miscommunication, however, and assume that you mean your character was asked out of the vehicle and has obliged. A search for weapons is still A-OK, However, if your character was immediately cuffed over that and wasn't given any real reasoning, that sounds like a complaint to forward up to Internal Affairs, who don't take such cases lightly in the slightest. However, if it was a roleplay quality thing, that is something to take up with the server's administration.
I hope this clears some things up and gives you insight on things. Additionally, I cordially invite you to sign up for a ride-along on one of your characters for the LSPD or the LSSD so you can get placed into the dynamics of various situations and perhaps garner a better understanding of cop culture and the thought process/breakdown behind certain actions and reactions!
Law enforcement also use canine backup so they can get away with sniffing the car. It's an officer safety thing!