Street vendors should have to buy a business/vending license, pay taxes, and be subject to inspection same as any brick and mortar place(In most cities that would be the case. I can’t beleive Pittsburgh wouldn’t as well). Workman’s comp would only apply if the vendor had hired help, which most don’t. Since most vendors probably take their trash with them when they leave, refuse collection fees would not really apply.
A brick and mortar place has a much higher overhead, but it also has much greater earning potential. A busy street vendor might gross a grand a day. A good storefront can do 10, maybe 20 times that.
You think the street vendors have an advantage? Sell your restaurant and buy a cart.