I guess AMZN must be feeling like they are vital infrastructure right now and won't get called on this sort of thing. And under the management of the current President the NLRB may not be able to prosecute such cases as vigorously as they have been known to do.
Whether we realize it or not we've been moving towards a neofeudal world where a large employer will effectively be the government and where individual workers will not have meaningful rights in their employment; and this will be as true of software engineers as it is of warehouse workers.