[adventured]

Walmart is commonly paying $12-$13/hr to first year employees around the US, Target is at a minimum $13/hr ($15/hr in 2020), Amazon is at $15/hr. Those are, broadly speaking, the new floor in American wages.

In cities, companies almost always have to pay more, so Walmart's wages on average are even higher in Detroit than in the middle of nowhere. They hoover up a lot of labor near or above $15/hr in places like Detroit.

Basically his wife's business is competing with massive labor absorbing machines that will pay at or above $15/hr. They also offer benefits. Small businesses (mom & pop types) that pay low wages and have tight margins often struggle to offer even basic competitive benefits, it's a very large additional cost in a business. So if she wants to take employees away from Walmart in Detroit, she might have to offer $18/hr instead.