There are second order effects on those, though. Fixed price contracts incentivize contractors to cut corners to make up for cost overruns or to pad their profi

There are second order effects on those, though. Fixed price contracts incentivize contractors to cut corners to make up for cost overruns or to pad their profits (doubly so if it’s a contractor who underbid to win the contract). Unless you’re willing to pay for a lot of govt oversight, many of those won’t be noticed until the contract is long complete. Even if noticed, you need an organization willing to engage in that legal fight. The administrative controls are lagging indicators at best, and administrative controls are usually one of the least preferable control mechanisms.