The short answer is: the restaurant raises prices. In effect, customers bear the expense directly.
One of the stupidest ideas some people believe is the notion that giving more money to one group of people causes that group to spend more money in ways that grow the economy, eventually benefiting all groups. Here we have the perfect refutation. Giving more money to restaurant workers causes restaurant patrons to endure an exactly equal loss of money. On balance there is no gain anywhere to anyone.
Call it the Happy Meal fallacy, or: There ain’t no such thing as a free lunch.