If there’s Federal money involved, most of it does trickle down to the worker.

Each contractor has to report what they paid to each employee so that nobody is screwed. The idea was that the government didn’t want jobs to be done by cheap labor and they set a wage floor that corresponds to local union labor rates.

The wage difference can be quite drastic - floggers pay jumps from $15 Pernod to about $32 per hour where I live.

More info: https://en.wikipedia.org/wiki/Davis–Bacon_Act_of_1931