The reason you can't let players sell stuff is that any booster could pay a player ludicrous amounts of money for anything. It would used as a recruiting tool. Come and play for us and I'll buy your practice jersey for thousands of dollars.
The best solution I've heard so far is to give every school in the country amnesty for past trangressions, but have incredibly strict monetary penalties to be levied on the universities for violations going forward. That way school officials won't sit idly by raking in cash while the football team runs wild. They'll actually have to do something about it.
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