It has to be the mindset - if you buy 99.95% of everything you own at a big box store then you must think that when you buy something privately CASH will have a big impact. But if you buy/sell a lot of items privately - you know it has no bearings - it's going to be cash.
From a business standpoint I can see where it may have an impact trading cash for services, not having to pay taxes, workman's comp etc for the revenue. Although I wouldn't know as I've never been offered or taken cash for services while I've owned my construction company.
