Tax dollars are paying for the regular work on the FIFO queue; satisfying the expedite request without impacting the regular work on the FIFO queue requires additional hours of work to be done in the same time, which costs money that the taxpayers, through representatives, have elected not to pay for. Rather than prohibiting such extra work outright, they permit it to be done, at the requesters expense.

It's a two-tiered system that favors those with more resources to expend, but it's not bribery.