Red tags get a lot of attention, they are seen by your supe, his boss the manager, and the managers boss the district manager. What I mean is red tag anything that is legit safety related and every time they bring up why so many red tags refer to keeping the drivers safe and needing help with repairs. Number one priority is keeping the drivers and the public safe every day, if a car has a safety related problem never ever ever let anyone pressure you to let it run. Your supe sounds like a very difficult person to work under already, that’s not acceptable for him to talk to you like you are a dog. That’s a whole different can of worms that needs to be squashed, tough love would be you need to stand up for yourself, and request help. In the meantime work as hard as you can, this might be a uphill fight for a while.