Consider the case of a restaurant which wants to occupy a local historical landmark. All goes swimmingly until the owner finds that the town requires ten more parking spots, but the owner cannot add those ten spots because half of the lot is wetlands. Why does the town require the parking? So the restaurants clientele won’t park along the street or in the adjacent lot (which the town also required)? Perhaps the owner is willing to take the risk that he’ll lose 10 tables by not having sufficient parking. That doesn’t matter to the zoning board of appeals, and now the property is back on the market, with the price adjusted for improvements.
Or that of the sporting goods store next to the bike trail, which jealously guards its parking spots with both gun and dog, despite having no observed customers or weekend hours.
In the former case, I would permit the business owner to accept the risk of lost business. And if the cars overflow into the street or the adjacent lot, then that’s more sales tax or parking ticket revenue for the town. And perhaps the neighbors can work out an arrangement. In the latter case, parking meters should do the trick.