Age Verifications: where do you draw the line?

choose all that applies

boosts appreciated 

against with the idea in principle (no other options applies)
a self-certifying checkbox is okay
offline verification of ID document is okay (via reading chip or OCR)
Credit card verification is okay (if you have one you are >18)
Mobile operator verification is okay (if you have a contract you are >18)
First party online verification is okay (upload ID or photo to the website you are using)
Third party online verification is okay (upload ID or photo to another website)
other (write in)
Poll ends at .
@kuriko if your government has a digital ID of all their citizens they could be able to certify you are of age in an anonymous way. (If they can hold all that private data inside of their government pants, that is. Which is a big "if")