You'd be mistaken. Public transit is extremely crowded in the centre during rush hour.
For example, two regional lines (RER B and D) need to share a tunnel in the middle of the city. They've been investigating digging another one for a long time, but, AFAIK. they haven't found an economical way of doing so. The solution is to try to move people to other lines, but those are already very crowded and I'm not aware of any project to build a new line inside of the city limits.
For example, two regional lines (RER B and D) need to share a tunnel in the middle of the city. They've been investigating digging another one for a long time, but, AFAIK. they haven't found an economical way of doing so. The solution is to try to move people to other lines, but those are already very crowded and I'm not aware of any project to build a new line inside of the city limits.