ha ha, you tricked here on PDF when you said you are machine driver.
Auditing assistant can not know well how the work is going on, on the project site. Only main constructor could have long term contract. other works like earth work, piling work or concrete work and etc should be considered as temperament works, which will be divided to many small contracts, will be signed with many subcontractor.
What chinese illegal workers do, in the photo I posted, there is earth work, what machine can not do.
delay of payment is very oft here , i think it does not happen USA.