Same thing occurs across the pond here, except the big hypocrisy is that kids (like, small kids) are developing CTE at positively astonishing, stomach-churning rates from participation in football (our version, the gridiron, not soccer), encouraged by coaches and parents to not only not avoid but to actively seek out full-on head-to-head collision hits, from tender ages in the PeeWee leagues - yet because football is so popular you never hear much traction gained by any movement to ban (or even seriously regulate) it, whereas boxing has been relegated to a fourth-rate sport in this country (being perceived as nearly the sole domain of inner city blacks or immigrant Latinos), and so is frequently lambasted every several years or whenever there's a high profile (especially if white) death.
It's definitely a class issue I believe. The sport is looked down upon save for when it is attracting the celeb crowd for a scheduled mega fight between two high profile mainstream, media friendly fighters. Then everyone is on board. I've heard about the numerous problems with brain damage and deaths in NFL as well as problems with PEDS. The only criticism I've seen is when looking back at the case with Aron Hernandez and the subsequent investigation into his brain scans which showed trauma. Though I believe all that coverage on the impact of NFL was a cynical ploy to attempt to absolve the murderer of responsibility from his actions rather than any concern for the sport itself.
Your absolutely right about the other sports, I think people just don't like the idea of people punching each other in the head.