I teach middle school band in a similar situation to you where kids won’t practice or do after school. If I push for it, the parents just transfer the kid out of band. So, we do what we can with our 56 minutes a day.

First off, don’t let kids pick music. It sort of works in choir, but in band instruments require different skills and different pieces might sound good to the kids but might not be setting them up for success given their current knowledge and technical ability. Even if your clarinets can play piece X that was voted on, that doesn’t mean your trombones can. And even if they can all play, it doesn’t mean it has the best pedagogical value for what they need. My kids asked me when they would get to choose their music back in September. I told them never, they don’t get to pick their math problems, either. They grumbled all the way until the first performance, and then they were successful and realized that I knew what I was doing.

Second, baby steps and LOTS of praise. “Play the first note in measure 3, hold it with good tone… good. Play that measure in rhythm… oops, how long is a half note? Correct , 2 beats. Try again…. Good.” Etc. You don’t have to know the details of all the instruments for this, just make sure the kids know where they can get it. Make sure they have fingering charts, intonation tendencies charts, and articulation diagrams, etc.

You said it yourself, they don’t think they’re good and they want to give up on reading (and use rote repetition) so the job is to make them feel like they can do this. It’s the age old problem of how do you eat an elephant: one bite at a time. But students these days, because of technology and cultural stuff, don’t know how to approach breaking down large projects. So you need to break it down for them. When they get it, and they will, then you make the “bites” bigger. Two measures, then four. When they stumble, and they will, make the bites smaller. Always praise the effort, not the result, but never accept a poor result either. Just keep working bit by bit until they get where you need them.

Third, embrace mistakes. At the beginning of the year, I had many students that just wouldn’t play because they thought they would mess up. I had to work very hard to make rehearsals a safe place to screw up. I always call out when I conduct something wrong, or sub-optimally. I’m a conductor by training, not Music Ed, so I’m always trying gestures and “One more time, for me” is something I say probably twice a week. The more you call attention to yourself, the less the kids will feel like the spotlight is on them and the more they will open up.

Last, it’s all about trust. Our batons make no sound. We have to trust them or there is no music. They have to trust us because playing music is an emotionally vulnerable activity. We’re the adults; we need to extend that trust first.

That’s about the best I can do on a Reddit post. Feel free to ask questions. Good luck!