If you check the article and then the one it links to, there were issues with building the road because they came upon a soft section of pumice sand that couldn’t support it the way the design was done. There’s arguments over whether they should have known or not but it’s not like the contractors just doubled the price to do the same work. The work was sold to them in a certain way based on designs they were handed and those designs didn’t work.

Given this is one of the most expensive roading projects ever, it’s clear this is an outlier situation.

I still think someone probably fucked up, but people fuck up and cost their employers millions all the time. Public sector isn’t immune to that.