Because, before minimum wage, we had people being paid the price of a loaf of bread for an entire day's labor. We had people being paid in "company scrip" only spendable in the company's own store at inflated prices, instead of real national currency.

Why, indeed.

In a society with a functioning safety net, minimum wage wouldn't be necessary. That wouldn't only be better for those who can't work at all. All employees would benefit, and eventually most businesses would as well. Here in USA I'm not sure if such a safety net is possible, but I hear good things about other societies.

Because, unlike what you suggested, policymakers are able to calibrate the minimum wage so it doesn't cause companies to go out of business.

Only about 2% of hourly paid workers earned federal minimum wage or less in 2018 in the US [1]. This percentage has been dropping over the past few decades. I think this implies that minimum wage has been calibrated to be low enough that it makes little difference overall.

[1] https://www.bls.gov/opub/reports/minimum-wage/2018/home.htm

That's misleading because the federal minimum wage is lower than more than half of state minimum wages.

Right, because the federal minimum wage is calibrated to be low enough that it doesn't make much difference.

In Texas, where the state minimum wage is the federal minimum wage, there are still only about 3% of hourly workers earning minimum wage or less.

Large corporations are making bigger profits than ever and the minimum wage isn't being calibrated to actually ensure a decent standard of living.