Well, they're not selling season tickets and individual tickets by seat number in advance that have to be refunded if the game is cancelled, are they? If HS sports have become this commercialized, I don't want to know about it.
If they are just charging at the gate, that's not a problem if the game is cancelled (other than the fact they lost the income).
And to answer your question, I am VERY OLD! Old enough to not have paid when I was in HS. Just walked in and sat down.