1) Here in the US and other now built-up countries, it's extremely expensive to displace existing interests and structures (both physical and legal, etc). People have built their lives, bought property, created interests, that have to be compensated to be moved out of the way. Even if a relatively neutral 3rd party could balance one interest against another, we simply have so many legal protections for people's interests that you now have to pay them heavily to make anything possible. Good for some reasons, bad for others, but that's a large part of makes it expensive. Just look at the ridiculous attempts to work around this at LaGuardia Airport. Never going to happen. Unless the government/state was forethinking enough to have reserved rights to some property to develop it, you now have to pay for the value it has accrued.
2) The other large part is that we almost now go looking for liability to protect ourselves against, whether real or perceived. This leads to endless environmental reviews, opportunities to object, lots of consultants required, conservative (read, high) costs, over engineering and over spec-ing. It has become an industry for everyone to get their cut, at the expense of the general welfare, but urged on by some small consituency, and they're all happy to stay employed to do so.
It's good for some things that property rights are being respected and the environment / issues are known before building something. But it has swung too far to that side I think.
And as sad as I am to say it, sometimes you wish that Elon Musk would do for local infrastructure what he did for government understanding of reasonable rocket costs. But this one is a lot harder to fix than offering for sale an alternative.