Reflect on it for a moment. In this exact case, people purchasing tickets into a concert, where there is a tremendous amount of business, why pay a third party for every credit card swipe? You get the exact same number of customers if you only accept cash. In many demographics, you actually get more customers from cash-only.
Sure, some promoters and business owners will evade taxes, but people do that anyway for all sorts of businesses. In this case, accepting cash only is not an indicator of attempting to evade taxes.
Because any manager knows that handling that much cash comes with risks. Someone standing at club door taking cash, sans cash register, is dangerous. Either money goes "missing" or someone gets robbed.
That has absolutely nothing to do with your comment that people who accept cash are engaging in illegal activity.
In an all cash business, the truth is you make money hand over fist. You can't count it fast enough, even with your door person skimming - which you already expect to happen. Besides, you don't have your door people stand around all night with loads of cash in their pockets.
Sure, some promoters and business owners will evade taxes, but people do that anyway for all sorts of businesses. In this case, accepting cash only is not an indicator of attempting to evade taxes.