Ever use an ATM? I am old enough to remember when, if you needed cash (and who did not), you went to the bank and stood on line with a personal check made out to cash. If you were really unfortunate you could be left cashless for the weekend, or in search of a friendly grocer who would cash your personal check.
You can ask, but don't insist on it. Some families are connected on social media and it works for them. Some teens don't want their parents seeing everything on their pages (and will block you from seeing things, which kind of defeats the purpose of being friends). Following your teens online opens up a can of worms, and you'll have to figure out how to negotiate that new relationship.