Nearly all government procurement requires a contract before work can be started or deliveries made.

If existing rules are followed, the contract includes the terms under which any progress payments are to be made, and if existing rules are followed properly the contract defines how the contractor will demonstrate that specific progress has been achieved before "progress payments" are made. It is probably unusual that the contractor can qualify to receive progress payments just by saying "well I've spent a lot of money so far so send me some."

There has always been significant latitude in what the contractor and the government are permitted to agree to do, but once the contract is signed, its agreements must be followed.

The failures in this system come from:

Not all contractors or all purchasing agents follow all the rules.

Not all contractors or all purchasing agents do a good enough job of following the rules to obtain the intended results. (I've seen a lot of really sloppy agreements.)

Nothing matters much if you've got a good relationship with an appropriately placed Senator or two, who can tack a rider on a bill to give you "the right special treatment."

Recently, "the right special treatment" seems to include cutting the budgets of regulators/oversight agencies to reduce their ability to monitor the contracts(?); but maybe that's just the way it looks and they really have our best interests at heart. All contractors are, after all, quite honest and will do what's best.

John