A Hobbyist role and a promoter role are different.
Of course promoters understate age. Show me one spa who doesn't. Are you going to go to a spa that advertises 60 year olds.? No, you are not. At least the majority aren't. It's a game of numbers.
Spas have a target market. So in reality they really don't care what a 20 year old thinks. That's not who they are targeting.
I may not agree with methods used, but I also don't waste my time arguing with spas telling them what I think. Go out, get a rub and a tug and be on your merry way. Life is way too short to try and prove someone is wrong on the internet.