I just assumed they were always hiring because of consistent growth.
According to the guy (forget his name. Wears a gold chain.) representing the union; Amazon fires a lot of employees. Many for no reason.
(I once read a restaurant success book. Everything he recommended made sence, except one, and it does make sence, but it's weaselly.
His recommendation to restaurants was to fire all employees every six months. Turn over the semi-skilled completely. His reasoning was a new employee didn't complain, didn't steal (this was before companies had cams everywhere, gps tracking, and wrist movment counters), and worked harder.)
I believe this is Amazon strategy.
It's usually a bit harder to fire union workers for no reason.
Fire them before they can see the inequities in the company.