Thank you for posting your experience in the Community. The Car Buying Service works by offering referrals to local dealers based off of specific automobiles you are looking for. The service does not just offer lower prices to USAA members, it is based on a referral service from USAA to certified dealers. We understand this matter is important to you. Your concerns will be shared with our Member Feedback Teams.
The USAA Car Buying Service is the same as TrueCar I believe. USAA doesn't regulate the dealers or decide which dealers are included/excluded.
It sucks you got overcharged, but car dealers are out to sell the cars for as much as possible, it is our responsibility to get all the discounts and negotiate the best price you can.
I never ask other people what they paid for their cars, especially if it is the same car I have because it will probably annoy me because they got a better price.