The majority of the time, I am way too chicken to talk with people either. Since I am not a tech and only self educated (from here and other websites about car seat safety), I don't feel like I can say anything. I did speak up the other day though! I had seen a mom at the library with 3 kids. The older 2 were twins, almost 4 years old, and the younger one was 2. After leaving the library, I saw her at the grocery store getting her kids in the car. I parked next to her and noticed that she had the bigger twin in a backless booster with the belt under his arm and the younger 2 in Evenflo seats with super loose harnesses and belly clips. I asked her if I could talk to her about her children's car seats and she seemed open to it so I talked to her about having the harnesses snug, clips at armpit level and making sure the boy in the booster had the shoulder belt on his shoulder. I wasn't familiar with her Evenflo seats (appeared to be FF only, red plain material, armrests, no front harness adjuster, looked fairly new so not expired) so I didn't know how to tighten them. She said her husband was the one who dealt with that kind of stuff so she would have him do it. My son's school is most likely having a car seat check event in a few weeks so I told her about it. She gave me her phone number so I can let her know for sure when the event will be. I hope she comes so some techs can help her!
ETA- I just looked at the Evenflo website and the seat she has in an Evenflo Chase in Steeple Chase. I've never played with one before so do not know anything about the seat.