I've worked for Amazon for just over 4 years, and I can honestly say that I have NEVER seen any of this.
1) Hourly rates have always been well above MW
2) Temporary workers are on temporary contracts -minimum of 40 hours p/w
3) P*ssing in bottles to meet targets? You've got us confused with truck drivers - it's called 'driver tizer' for a reason.
I agree that they do need to get their house in order as regards paying taxes, but that's our governments allowing them to get away with it, they're just exploiting an already crooked system.