Which bases have contract security? The vast majority are not contractors, but direct employees to the command hired under the GS-0085 or GS-0083 fields. I'm not aware of any stateside with contract security.
Also, why is it bullshit?
Yup. This was the norm when I was in the USMC from 2007-2011. Sometimes the SRT would be posted at the gate doing it, sometimes posted at various roads on base.
Getting excited about random searches on a military base as if it's news, is really odd to me.
Not really. That's pretty standard, it's the way they did it with us and the way we were taught to do vehicle searches as well. Have the driver/owner open all the doors, hatches, gas cap cover, ect, then stand all the people facing away from the car.