The thing about tax evasion is everyone is brought up hearing all the crazy stories about the IRS taking people down for tax evasion. Most people are terrified of the IRS and assume their chances of getting caught are much higher than they really are. Bags are basically the opposite. Kids assume they are untouchable when it comes to bags getting dropped. Players hardly ever get caught and all the big cases of players getting caught, nothing ever happens to the player(I am exclusively talking about football here) only the school gets in trouble.
Even with this in mind. Tons of very wealthy people still try and cheat the IRS for a much smaller percentage of their net worth compared to a bag and Surtain.
I get what you are saying and that is very respectable that you wouldn't take the bag, BUT you are probably in the minority. It doesn't take a power hungry scumbag to be willing to partake in a victimless crime that will net them a couple hundred thousand.