I don’t understand what you’re thinking. The commission isn’t the major expense; why should eliminating it widen the bid-ask spread or total trading cost to any significant degree?
You said “When you buy/sell stock, the transaction money is made on the bid-ask spread. At, say, 2 cents a share, a 1000 share order will be $20, which is more than the commission they say they charge.”
I said a lot of stocks trade with a higher spread than 2 cents right now. I’ve watched some that a 50 cent spread is not uncommon.