I suspect it has a lot to do with building in urbanized areas and using construction and siting methods that care about things like public input and how the environment is affected. (Note: I do not deny that the process can be twisted to suit a particular goal of a small minority--see also Sound Transit's East Link planning through Bellevue, WA.)
Instead of the days of the "city fathers" coming in and declaring that a thing will be built in a place and that which exists can either get out of the way or get flattened--and the thing being built in a way that benefits those who greased the right palms with the public coming in a distant second or third--we study, plan, and consider a lot more.
As a secondary bit, we also don't have the financial capacity, either by accident or intent of the legislature and voters. Many projects are built with bonding authority backed by voter-approved taxes. The legislature of an area restricts what authority and taxes can be used and in what quantities. Dallas Area Rapid Transit's light rail system was built with a 1% sales tax in member cities...and it still doesn't extend to every city that was a charter member. Sound Transit's light rail and express bus system was built with a combination of taxes, mostly on vehicle registrations and sales, that are under periodic assault from statewide initiatives. Many countries have a "land bank" where the national or provincial/state government "front" the money for the local bonds. (Like Canada and British Columbia did in Vancouver.) Most U.S. states do not.
We "did this" to ourselves. It's not the construction, it's the mechanics of getting there.
