Well to be fair, most construction projects are bid on a fixed-price basis with overages, and there's normally a limitation of when stuff can be changed.

Generally, the optimal strategy for a construction company/contractor is to go in with a low fixed price bid and screw them on the extras that your specialists have identified will be necessary, but the general contractor/engineers have missed.

Source: I used to price construction jobs back in the day, and heard a lot of horror/joy stories. I think my college education was partially funded by these kinds of mess-ups, as my dad worked in construction.