Some have argued that the government should pay people to get the vaccine; it's a standard economic solution and make sense in some circumstances (like if people don't get the vaccine because they don't want to take time off work). Pigouvian subsidies make sense.
But here it's tricky because government payments to get some medicine might make suspicious people more suspicious. ("They have to pay people to take it! Now I know there's a tracker!") This restaurant offers a nice work-around as the payment comes from a restaurant rather than the federal government.
(Of course conspiracy theorists would just argue the government's really pulling the strings but on the margin this approach could help a lot. Especially if lots of other venues follow suit. And the discount IS huge: half off!)