I haven't worked in one owned by Amazon, but I've worked in a warehouse. As far as I know most of them are about 50C warmer than the ones I worked in, as far as I know, there's no 80kg amazon packages frozen at -25C so I'd say they have it pretty easy.
That warehouse certainly didn't have robots to bring us our packages for scanning by laser gun either.
Yeah, real statistics must be made. However this opinion is so universal and frequently voiced by the workers that not sharing it would be just as wrong as relying purely on anecdata.
The society here is not too divided. It's normal to meet, talk and drink beer with people of other occupations. Every time someone at a bar tells me they work at a warehouse, they will soon be raving about how much better things are thanks to Amazon. You can overhear these conversations at bus stops, at the doctor, etc.
That warehouse certainly didn't have robots to bring us our packages for scanning by laser gun either.