They'd simply cut wages when the labor supply shock recedes and labor is in surplus again. Businesses do not pay the minimum wage out of the goodness of their hearts; on the contrary, it communicates "we'd pay you less if we could, the law simply doesn't allow us to."
But note also that there are people one might be willing to gamble on employing at $12/hour but that don't offer a positive return at capital at $15/hour.
I think minimum wage laws are important, but that reducing the supply of labor will do more to push up the wages of the lowest earners.
Then pass UBI instead and drop the minimum wage laws (there's no need for them if UBI were a thing). Problem solved.
Right now the problem is in the power dynamic between companies and employees - the dynamic is very unbalanced in the companies favor. In "Bullshit Jobs" Graeber compares the current system to a Dom-Sub relationship with no safeword for the "fake-competitive" industries that are not unionized.
