Though they would also need to be financially sound at the time they became a full on citizen, own a car (to make us of the day pass free parking), and be able to take the time off, to actually go see these parks.
Remembering the voucher kicks in on the day of becoming a citizen and then expires exactly in exactly 1 year.
I guarantee you if someone becomes a citizen in their teens and originally immigrated on their own with no family (which happens), they would more then likely not benefit from this, and probably not even have the means to see these parks in that one year window, and make use of the free day pass voucher for free parking…