At least with major projects this is 100% the case. Had a buddy involved in a state legislature said one of the reasons there is so much road work and construction going on all the time is because it is one of the easiest ways to disguise corruption and embezzlement.
As an example in a 5 year project for a new overpass you can have literally 1000s of different contractors involved in the work and it becomes very difficult to notice and prove that Joe's Cement company never showed up to pour the liminal substrate pylons like they were paid $10k to do.
My favorite New York "Joe's Cement" story is that when they were expanding Islip airport, a mob-owned cement company that was giving kickbacks to the local county government poured the ramp pad WAY under the specified thickness using unreinforced concrete, so of course the first Southwest plane to arrive damaged it.
Don't hire a mob-owned cement company, you say? Tough noogies, In NY, at least at that time, they were all mob-owned.
As an example in a 5 year project for a new overpass you can have literally 1000s of different contractors involved in the work and it becomes very difficult to notice and prove that Joe's Cement company never showed up to pour the liminal substrate pylons like they were paid $10k to do.