The costs? Basically it comes down to things like roads, water, sewer, etc. being amortized over fewer people:

https://usa.streetsblog.org/2015/03/05/sprawl-costs-the-publ...

https://www.strongtowns.org/journal/2019/2/5/suburban-infras...

Re: costs to cities, mostly focused on the extensive roadworks to serve solo car commuters - those are expensive and converted a lot of neighborhoods into something which consumes but does not generate tax income, and things like parking don’t generate much income, and all of that comes at a hefty cost to health & quality of life.

That's the basic premise made by StongTowns.org. It's hard to pick a single post to start but the one about Layfayette, Louisiana is a good case study and a good place to dive in, imo.

https://www.strongtowns.org/journal/2017/1/9/the-real-reason...