> Isn't Amazon getting to the point where they're having trouble finding employee candidates they haven't previously fired?
This apparently happened somewhere in a rural area with a small local population. It's obviously not going to happen at a warehouse in, say, New Jersey.
And to the extent that it actually happens somewhere it's not like their response would be hard to predict. Calculate how much they would have to increase local wages to expand the candidate pool enough, see if this is less than it costs to move the warehouse somewhere with a larger pool of workers, if not then move the warehouse.
Notice that Amazon warehouse workers get paid more than minimum wage. This is why. Unskilled workers don't have zero leverage, they just don't have much.