That presumes that Amazon can't substantially automate their labor away, which is exactly what they'll aggressively do if you raise said cost of labor a lot.

The actual end result will be far greater tax payer cost for fully subsidizing people that no longer have any employment, versus partial subsidization.

There isn't an advanced economy in all of Europe for example that doesn't use heavy government (aka the top 50% of income earners) subsidization for the benefit of the bottom 50% of earners. The healthcare systems in Britain and France? The bottom 50% of employed persons are not primarily paying for those very expensive benefits, they're receiving large government subsidies that help offset their terrible pay, in the form of all sorts of welfare benefits. Britain for example has such a low median wage, it barely qualifies them as the 50th poorest US state, how do you think their bottom 50% of workers get by if not through huge subsidies via the government to offset that terrible pay? For some reason when companies in the US do the same exact thing, it's evil.