Age Verifications: where do you draw the line?

choose all that applies

boosts appreciated 

against with the idea in principle (no other options applies)
34.8%
a self-certifying checkbox is okay
47.9%
offline verification of ID document is okay (via reading chip or OCR)
7.2%
Credit card verification is okay (if you have one you are >18)
5.9%
Mobile operator verification is okay (if you have a contract you are >18)
2.7%
First party online verification is okay (upload ID or photo to the website you are using)
0.4%
Third party online verification is okay (upload ID or photo to another website)
0.2%
other (write in)
1%
Poll ended at .

@kuriko

I'm fine with credit card verification in the form of a one time fee, only for things where keeping children out is a service to the other users.