Once upon a time you had to "make" the band.  Meaning, you showed up at summer band camp your first year, and if you didn't perform well and show the right attitude, you weren't in the band.

At some point band directors got hamstrung by spineless principals buckling under the pressure of idiot parents that thought every kid deserved to be in band (well, not every kid, but definitely THEIR kid).  Gee whiz...I never saw Fumble Fingers Fudpucker wobbling down the sideline to fumble the winning touchdown pass...doesn't every kid deserve to play football even if he can't run and can't catch and can't remember what a post pattern is?  Doesn't Larry the Midget deserve to play Basketball even though he couldn't sink a free throw with a laser-sighted basketball cannon?

Wanna turn some heads?  Ask to see your principal with your band director for a talk.  Tell him you really want a good band, and the policy of letting people in that don't care is hurting morale, and making the school look stupid.  Use my examples of sports policies.  Principals often want all the kids to fear him/her.  He/she is the holder of judgement and punishment.  BS.  You're the student, he's YOUR servant.  If you wanna fix it, it's gonna take more balls than a blog post requires.

Being a band director was the most frustrating job I ever had.  I'll never go back.

Oh how ironic, I'm a horn player, too.  Actually, I went to college for music and now I teach it so here's some advice:

Just get through it, with a smile, set a good example, be enthusiastic about your section and I promise it will seem better.  Don't let others spoil the music making process for you.  Transcedence is a good thing. 

Do you plan on studying music in college? 

I have a story that sort of relates to what you are going through:

In college I was in every ensemble imaginable.  I played many gigs on the side and always worked my ass off on whatever rep I could get my hands on.  Even though I was putting in all of these hours of practice, the seating in orchestra always went by seniority.  I remember getting so angry because when I was a sophomore, I could easily outplay the seniors.  I then became very bitter about playing in all of these groups because like yourself, I felt like the directors didn't get it.  Looking back, now I wished I had been more positive about all of it instead of wearing it like a burden, and just enjoyed playing music when I was always given the opportunity.  Now it seems like I have no time to practice or play in a performing group!

You're in a tough spot.  My daughter played in school bands in middle & high school as well as a couple of world acclaimed local marching bands.  In her case, the director of her HS  band totally blew the experience for her.  He loved music but absolutely hated kids.

My story is similar to hers (and to some extent, yours).  I'm 57 and play first chair in a pretty good community band.  My point - hang in.  You need to focus more on what your getting from the experience than the frustration you have over the lack of commitment from the other players.  Alison speaks well. 

Good luck.