Firstly, once people get in their car to drive, it is hard to get them out of it to do part of their trip on public transportation. Especially if there is no convention transportation for their trip, which is the case for suburb to suburb commuters

Secondly, at least in Paris the suburban transport system is beyond saturation. The metro line 13 is at 120% capacity ; very often on the RER A line you have to let 3 or 4 trains pass before getting in. Adding passengers is nearly impossible...

Un roi sans divertissement est un homme plein de misères