There's a common pattern with public transportation projects in North America in general.

When a project is built city planners use the opportunity to widen streets, roads, build or upgrade bridges, and do this all in a effort to not diminish the amount of lanes previously available to vehicle traffic. Something even adding a new lane where one did not exist beforehand.

This means when new stations go in, or there is any above ground transit corridor, a good chunk of the cash gets funneled into "car centric initiatives" as opposed being solely allocated for the transit line.

In the area I live we have a tram line that went in not to long ago. It has both above and below ground sections. Along the whole corridor the city street was repaved, and at the street level routes the street was completely reconfigured and widened. This includes sidewalks, benches, planting, landscape, curbs, mediums, traffic lights and signaling, electrical, and storm water. The costs ballooned obviously.

It's almost like city planners were working on the assumption the public was still going to choose to drive, as opposed to take the new transit line. So all efforts and funds were put to work in a way not to inconvenience drive in the slightest.

So in the end the project costs are higher, and the public does not question all the shiny new car infrastructure, but then proceeds to ask why the transit line was so expensive in the end.