Not just rotating pools of proxies but sometimes shady gray market residential proxies, so that you can appear to be coming from hundreds or thousands of unique geographically distributed end-user DOCSIS3/ADSL2+/VDSL2/GPON/whatever last mile end user customer netblocks.
If you want to go down a rabbit hole of shady proxies run on compromised/trojaned end user SOHO routers or PCs, google "residential proxies for sale"
Once worked for a place using this to scrape search engines.
It's amazing how easy and comparatively cheap it is to get access to thousands of residential IPs. Is it via spyware running on people's machines? Shady people working at ISPs doing nefarious things for cash? We never knew....
The key thing to know is that if you want your traffic to come from an IP "in" some other country (according to geolocation databases anyway) it's really only a few bucks a month to get a proxy. Most of them have poor IP reputation so they suck to use on Google, but work very well for everything else out there...
> Is it via spyware running on people's machines? Shady people working at ISPs doing nefarious things for cash?
Might be as simple as https://hola.org/ & https://luminati.io/ - "unblock a website, download our VPN client", meaning you "unblock" by using somebody else's line. And the also sell access at luminati. Most users aren't aware of the implications.
If you want to go down a rabbit hole of shady proxies run on compromised/trojaned end user SOHO routers or PCs, google "residential proxies for sale"
https://www.google.com/search?client=ubuntu&channel=fs&q=res...