Edit: the article says "Adults would be forced to enter personal information like passport or credit card details", so I guess other forms of ID with a date of birth would be accepted.
See https://www.gov.uk/government/publications/introducing-govuk...
It will be a drastic change to pivot the company from one where the customer is the product to the customer.
Credit card input also introduces friction and bounce rate of user signup. This would hurt Facebook's user growth and MAU KPIs
People tend to get them for online shopping abroad, and for travels out of their currency zone as a back up.
11+ with parental permission. I had one around that age.
If you can login to your government tax account, or apply for a DBS, you'll be able to prove your identity.