Are there any security mechanisms that could be activated when somebody logins to the same Google Account multiple times from Tor (with IPs from different countries)?
Google blocks the account out if one tries to access via any IP address other than the address it was originally established at. It may ask for a phone number or other information before unblocking the account. This behavior is not limited to Tor. If one try to use VPN or even physically move to different location with new IP address this security feature (bug) will activate. If you do not like this feature (bug) use different provider.
Google by default blocks connections from different areas, sure as if I logged in China (not my homeland) Google would require me to verify with my phone number or e-mail backup address. This feature cannot be disabled, and it's for the safety of your account.