There are no problems with children. Although my little relative does live here in Florida, I've purchased FL resident passes for him through my
AAA and have never had to show ID for him.
On the other hand, my wife's mother asked if she could have a FL resident pass for her visiting granddaughter and the answer was no.
You will be asked to show valid photo ID (driver license, sherrif's ID, passport, student (current year) ID, military ID, ect.) when presenting the voucher at the gate for the actual pass if you are an adult.
California DL is not as strict. We had a military family member with us, who purchased our tickets on base (that also indicated on them that you needed to be a California resident) we got to the gate, not sure that they'd allow us to use the passes, but they did. They didn't want to see our ID. We got the impression that because the military person was with us, we were ok. Not sure if that was the real case or not, but we weren't going to argue with them.
If you are used to DL, you may be lulled into thinking that Florida won't check, but WDW does. (Again, for adults).