[ufmace]

I presume it's about making the income appear to be plausible to a tax inspector.

If you actually sell illegal drugs as a business, but claim to have a pizza place on your tax returns, the government might inspect you someday. If they find that you don't have any big pizza ovens, routine large orders for ingredients, staff of delivery drivers, piles of receipts from customers, etc, then they'll probably get suspicious very fast.

If you do make and deliver at least some pizzas on a appropriate scale, then things get a lot harder. They'd have to run down all of your customers and ask them if they ordered and received pizza, check if the dough order receipts are real and match the expected volume, are the delivery drivers real and how much work do they do, etc. Much more work to run down, and who has time for that? You could probably get away with it, for a while at least, as long as you didn't screw something else up.