Yes, it is a positive. It puts more capital in private hands where it gets used more efficiently.
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And gives a competitive advantage to the dishonest.
It benefits the informal(underground) economy but not the formal economy.
In the US, some small business do this but many will limit it because it detracts from building equity or value in the business, which detracts from the price that the business owner can sell the business for and/or makes it harder to borrow money to expand the business.
But for a business that relies mostly on labor for profit, rather than selling, it is more likely. Its harder to build "blue sky" in a labor dominated business.
During economic downturns the informal economy always expands as the formal economy contracts, because as revenue shrinks more temporarily shift to cash transactions to avoid taxes as a way of offsetting falling revenue. Then as the economy recovers, they will shift back to reported transaction.
Some places, like Mexico, the informal economy is much larger than the formal economy.