[eck]

> What are the odds that I'm going to get a payout?

The expected value of slot machines is negative too. Humans have a psychological weakness for "Just one more, I haven't won in a while, I'm due." In this case though it wouldn't even cost money to play.

[shortstuffsushi]

The expected value of slot machines is negative, but there is that slight chance of making a significant amount of money. That sort of "lottery odds" behavior doesn't really work here, imo.

[rsuelzer]

Then make it a lottery. Payouts for certain licence plates at certain times of the day.