A test in economics

One popular economic professor writes the following. Find a mistake in his reasoning. You have one minute. Seriously, it's easy.

"But there is a silver lining to this cloud and indeed it seems that consumers will fare okay in this world of growing fraud, even if we feel increasingly harried.
Think just for a moment about what fraud means. Fraud means that the seller is lowering costs, raising revenue and enjoying higher profits.
In the short run that is bad for the customer. But in the long run it means there will be more suppliers and more competition for our business and thus lower prices.
Take the proverbial cheat auto mechanic. Maybe half the time he will charge you even when he hasn’t done any useful fixing. But in the long run that extra revenue will draw about twice as many auto mechanics into the industry to compete for your money. Yes, they will be ripping you off half the time but prices will fall by a roughly proportionate amount.
In the long run, you, as a consumer, will do okay. You pay twice as often as you ought to, but as a consolation each time you pay only about half as much."