They ask for driver's license because it is typical that people in the US drive. However, driver's license isn't required for anything other than driving. A legal photo ID is sufficient for most things. ;-)
And if you do not drive, then you get a "state ID card" from the DMV. That's what I did before I was 16 and went to Canada.
( I don't know the laws about children - perhaps because they are underage....)