In Russia developers of face search engines like findface or searchface usually scrape images from largest Russian social network, VK. They usually do it follow

In Russia developers of face search engines like findface or searchface usually scrape images from largest Russian social network, VK. They usually do it following that motto about asking for forgiveness, and there are no effective legal countermeasures anyway. I think there should be no problem to scrape other social networks like Facebook, Instagram or Twitter from the countries where there are no legal restrictions and the photos are considered to be a "public data". You can outsource face recognition tasks to such countries.