On the topic of criminal behavior, it's also worth noting that doing business cash-only makes you a more tempting target for robbery; if you did almost all of your transactions via credit or debit cards, you'd have very little in the till for someone to steal.
Since old habits die hard, these small businesses used to under report income despite the trail of evidence left by credit card processors. So, IRS came in and imposed a rule on these processors: send us a copy of payments paid to Mr Small Business X--and that copy is called 1099-K. This is like W2, 1099-MISC, 1099-INT.
Basically, the tax man wants records from the third parties, since self-reported ones are mostly under reported.
Some processors charge merchants for this reporting services to the IRS which further drives up Merchant Services cost.