This is actually not just about Tor. Their definition of "suspicious" is quite liberal and naive to be honest. As an anecdote, I get ~1 captcha per month becau

This is actually not just about Tor. Their definition of "suspicious" is quite liberal and naive to be honest. As an anecdote, I get ~1 captcha per month because I live in Eastern Europe. Add to that Linux, Firefox, NoScript and you're in for a fun ride.