I'm going to agree with Rick that the overall standard of living is significantly higher today than it used to be.
My parents never bought any music instruments for me. Other than the trumpets, clarinets, flutes or alto saxes hardly any parent bought band instruments for their kids in the early 60's. The rest of us played school owned instruments. I never even saw a tuba, let alone played one in high school. We had a couple of National Guard surplus sousaphones.
The school was small, as schools tended to be in those days. This was pre-busing and small towns had small schools. We had marching and concert band - not orchestra. That was the norm in those days. I don't recall any band member from my high school becoming a music major in college.
It wasn't a question of being poor, although parents in the 60's had a lot less disposable income than today.
By the time I had my own kids I was making more money than my father ever did. More disposable income. And I disposed of it freely.
My daughter had her own flute in band. My son had his own trombone. My daughter took piano lessons from the time she was 5. We bought an entry level piano, which she had completely worn the action out on by the time she was 12. So we bought a much better piano to replace it. That piano costs us $10k in 1988. We still have it and it still plays like new. And if our daughter ever gets a larger house she'll finally get it out of our living room
The point is that I can easily see how a supportive parent can and will spend a fair amount of money on a tuba for their kid. Yes, tuba's are expensive, but pianos and violins can be even more expensive. Even in the 60's a lot of homes had pianos if their kids took lessons.
The fact that we old farts didn't have this and that in our younger years doesn't make that a virtue or a reason to not provide those things for our own kids, if we can. Do our kids appreciate it? About as much as we appreciated what we had when we were that age, I'd say.