In my location (West Coast, USA) local tradespeople will give me a 10% discount for paying with cash. That's more than they'd pay in check or credit card proces

In my location (West Coast, USA) local tradespeople will give me a 10% discount for paying with cash. That's more than they'd pay in check or credit card processing fees. I assumed that taxi drivers' preference for cash was for basically the same reason: under-reporting income to tax authorities.