If your contract+fees is more than ~$41/mo youre overpaying and the financing is built in there.
The carriers arent giving you a free present.
No? Contract-free is $25/month per line. On-contract is $40/month. That's a $15 difference.
I know they aren't giving a free present, but what they are doing is making it cheaper to be on-contract. That makes economic sense for them, because if they can get me to be on a contract, they can keep me (almost) guaranteed for 2 years. Hence the total cost of ownership is (slightly) lower.