Amazon will do that the minute the math works out anyway. Encouraging workers to put up with worse and worse conditions out of fear of automation is just a race to the bottom that inevitably ends with automation anyway.
The scare tactics worked in much of the country; the federal minimum wage hasn't budged since 2009 and most states are at the same level. What did we get in exchange for that act of kindness towards the service sector? More self-checkout lanes and kiosks.