It's difficult because I've never had Comcast (I pay my £10/month BBC fee that hasn't gone up in years with pleasure) but I'd probably start by saying that Comcast is not a scarce good.

If it wasn't scarce then it would be cheaper. The problem is that it is scarce, artificially, as a result of regulatory capture etc.

Which is the same reason housing in places like SF is so expensive. Artificial scarcity as a result of zoning rules that make construction prohibitively expensive or otherwise inhibit it from increasing the housing supply.

Houston metro has more people than SF metro, so why does housing cost more in SF? Because there is less of it.

To bring us back onto the topic, Manhattan is a scarce resource, and there's nothing artificial about that fact.

There's plenty more space in the up and down direction. Bridges and tunnels could be used to add car or other vehicle capacity.

This thread is about transportation, not office or resi space.

Edit - I see you've changed your message. How does a bridge over water add road capacity to a peninsula?

It doesn't. There may be a other materials that bridges can go over, however.

Your solution to road congestion on a densely-populated peninsula is more roads. Got it.

It's not just more roads, although more roads are one of the things it is possible to create.

You can also create more housing, so people are closer to their jobs and have to travel fewer miles. Manhattan has higher density than most places, but it also has more people, and would you be surprised to learn that the zoning in most of NYC no longer allows the buildings that are currently in Manhattan to be built almost anywhere? So as a result you can't create more of them and people who might like to live in Manhattan instead live in the suburbs around the city and drive into the city in a car.

You can also create things that aren't roads, like subways, which then allow you to remove cars and buses (and bus lanes) from the roads when it becomes viable for more people to take the subway, which reduces road congestion.