There are lots of brass players at DS's (private) school.
Why?
They do six introductory free lessons in Year 4 of a brass or woodwind instrument, and then can pay for lessons and hire an instrument from the school for the rest of the year. (They do the same in year 3 with strings.)
There are loads of opportunities to play with various ensembles, including jazz bands, as well as more classical ensembles.
It is seen as a "normal" thing to do. Lots of the (non music) teachers play instruments, including a "cool" teacher who plays the euphonium. At last year's prize giving, there was a "mighty orchestra" where at least half the students, and all the peripatetic music teachers and many of the classroom teachers played.
The school has both a junior and senior school. So, while DS is the only bassoonist (tenoroon, actually) in the junior school, there are others in the senior school, so it is worth a teacher coming in, as it's to teach 4 students, not just one. (I know bassoon is woodwind, not brass, but it's similar in that it's quite rare.)
The parents can (one assumes) afford to pay for lessons, or they wouldn't have children at a private school.