it’s normal for government. bid low and get what you want with cost overruns.
There are other ways that government contracts balloon out of control as well. I worked for Martin Marietta in the early-80s. One of our contracts was the MX (Peacekeeper) missile. It was a crucial weapons system and played a big role in the eventual demise of the Soviet Union, but it was a “cost-plus” contract, meaning that it had no fixed upper limit and the company could charge whatever it needed to against it based upon their cost plus a percentage on top of that. Well, what do you think happened? Anytime some other contract with a fixed cost started to run up against its cost ceiling, we were told to just charge those costs against the MX contract.
It eventually exploded into a huge scandal, and you can be sure that similar practices were (and may still be) going on throughout the defense industry.