Why Google captcha is aggressive when it detects TOR Exit Node!

[patkim]

Sometimes I use TOR to browse the net. Usual browsing is okay but whenever I attempt to register on some site that requires Google captcha verification, it throws at least 15 - 20 repeated captcha image slides before verification is thru.

Usually it just takes one correctly solved captcha otherwise.

Does anyone know why Google captcha is so aggressive when it detects TOR Exit Node?
Is there any rationale behind multiple captcha logic? Just curious.

 

[cute.bandar]

Basically google has a limit for how many queries can be made, per hour/minute etc. Any more than a certain limit then there is a cost, legally.
Lot of people (try) to use Tor for sending automated queries for free. Hence when google detects lots of requests from an IP, the captcha comes!

 

[kunnusingh]

This is because of abuse, TOR node IPs are to much abused by various people.

Main reason is this IPs are blacklisted on various website, etc and in result google mark it as a bad IP.