It's hard to put down a technically legal, as far as text of law goes, practice. Especially when there are no complaints to use as a base because all contenders for the contract were similarly shady. And sometimes some $RANDOM gets the contract because nobody serious will take it, thanks to anti-corruption/anti-loss measures that the populous voted in that made the contract impossible. So Honest John Federal takes the contract and finds a suitably desperate student/outsources it to cheapest vendor possible.

Meanwhile auditors (unless burned out) would love to get the contractors and buyer staked in court, but technically all checkboxes on the checklist are checked (pun intended) and there's no obvious better candidate to use as counter example.