Scott Alexander has a great post with lots of data on this:
http://slatestarcodex.com/2017/02/09/considerations-on-cost-...
The numbers are pretty incredible. There is no single clear answer as to the cause of it all unfortunately. It looks like funds becoming available allow a whole bunch of areas to suck more and more money arguably without providing a lot of value. Universities compete to have the biggest stadiums and the most luxurious dorms. Hospitals pay more and more people to manage, oversee, verify, systematize and inefficiently computerize everything.
In a lot of areas, we seem to pay a lot to achieve marginally safer conditions. In the case of health care, if paying 5x the cost extends the life of an additional 0.1% of patients, it's hard for deciders to justify not doing that spending since saving 0.1% of people in hospitals is still saving a ton of people.
Construction projects are like that too, you might be able make construction safer, have 1% fewer injuries, if you are willing to pay 5X more for the project. These safer, but much slower methods often become mandatory.
How do you decide on these trade-offs though?