Yes the original purchaser is still on the hook for the payments. However in America today there are absolutely tons of people who are on the hook for payments

Yes the original purchaser is still on the hook for the payments. However in America today there are absolutely tons of people who are on the hook for payments that they simply do not make. In the tech world people are generally financially well off that they don't realize this. There are people that will just shrug at the fact they owe money to a company. At least if the phone is locked the carrier can just cut off service as an attempt to hopefully get payment as the phone is rendered useless without payment. However with unlocked phones theres no way for them to get the money they are owed. It's insanely expensive for them to go after each and every subcriber legally that doesnt pay. Remember, they are loaning these devices to subscribers who cannot pay the entire cost upfront with the hope they will pay them back over the course of the contract. Unlocking the phone gets rid of the one collateral they have. Thats the reason your account must be in good standing to unlock early with every major carrier and why some do credit checks.