If it was costing them serious business, presumably they would change their IPs, etc. Where as Amazon are unlikely to because sending email isn't their core business.
I'm aware of AWS firewall blocks at various sites.
Have a look around at some of the forums for web masters, and you'll find wholesale blacklisting of these server farms is regularly discussed. And implemented.
The presumption being that outbound connects from these server farms are usually something where the VPS has vastly more bandwidth, or bugs, or breaches; where the attackers and the spammers and the scrapers have quickly adopted or targeted these server farms just because of their capabilities.
And yes, there are well-intentioned folks using AWS that are getting painted with this same brush.