I can't speak to why someone chooses to fish alone. Maybe they don't know any kids that they can put in their boat. Payout is the same if you cash with a kid in the boat. I've fished with a kid at the last two regular season events on Fork. Payouts on most trails are determined by the number of paid teams. Since BC covers the Junior's half of the entry, payout is the same.
I haven't thought about the cheating aspect, but I think you'd be better off doing that with a family member or best friend. Kids talk.