It is mostly not about late discovered faults, but adapting the software to changing environments outside of the product's code. The customer on the other hand

It is mostly not about late discovered faults, but adapting the software to changing environments outside of the product's code. The customer on the other hand is mostly very less interested in getting their money back, but in a functioning system. Code in most project agreements is already in the hands of the customer, or at the very least placed in escrow. And when you say 'the developer pays', that is 'the customer pays', as the insurance premium would be embedded in the project cost. Apart from the insurance industry, who wins here?