Apple Pay does not have an age restriction. The de facto age restriction is set by banks, and federal banking regulations. If your son is under 18 and has an Apple Cash account, who set it up? If a parent or guardian did, using Apple Family Sharing and Apple Family Cash, there should not be an issue. If your son did and is under 18 he provided false information (committed fraud) and Green Dot Bank has locked his account. Apple Cash is issued and serviced by Green Dot Bank. You can contact them using the information below.
Set up and use Apple Cash Family - Apple Support
How Family Sharing works - Apple Support
How to set up Family Sharing on your iPhone, iPad, or Mac - Apple Support
Apple Cash - Apple
Verify your identity for Apple Card or Apple Cash - Apple Support
Apple Cash is serviced and issued by Green Dot Bank. Please contact an Apple Cash Specialist at Green Dot Bank.
Contact Green Dot Bank:
• call (877) 233-8552
• disputes at P.O. Box 9, West Chester, Ohio
• general customer service at P.O. Box 1070, West Chester, Ohio 45071
• visit www.greendot.com
https://applecash.greendot.com/termsconditions/