Ignorance of Amazon culture and practices, greed, visa issues, many don't believe it's as bad as it is until they experience it. Many use Amazon as a stepping stone because it looks good on your resume and will guarantee you an interview at most places. For the fulfillment centers folks and blue collar ops; desperation.

Retention for engineers is really low, some say as low as 12 months. So thousands work there, but many do not stay. Also the reason why their compensation is mostly in stock. They know you won't last.

This is all gleaned from friends who work there or have worked there. It's a place you want to be seen working, but doesn't work out for many.