Other mistake: Will did not have enough time to place into the pot at the poker game. For those at the end of a hand, they each have contributed a minimum of an equal percent based on the number of people in the hand. There were potentially 5 people at the start of the hand, and Will did not have enough to cover 20% of the final pot. He would have needed well over 200 years available, and we know he had a little over 100.
Revealing mistake: When Wil is showing Sylvia how to shoot, and she fires, Justin Timberlake can be seen wearing earplugs. When the scene cuts, he no longer is wearing them.
Chosen answer: When they turn 25, their built-in clock starts counting down from 1 year. Since time is the currency, they must then work and contribute to the economy, in order to earn time and survive. The government gives that one year of time to each person, as both a population control measure (if they don't work and earn, they'll die) and an economic incentive.
David R Turner