On the other hand, if the on-ramp of a highway would only let cars through for one minute every 10 minutes (which would be considered a good service interval for any suburban public transit), the demand for roadspace would likely be a bit less elastic. Ditto, if the highway would only go to a set of destinations with no connections.
Motorists can embark on a trip any time, join the highway any time, and take any exit, and continue from there to local destinations. This free schedule suits way more people than fixed departures to fixed destinations using public transit.
Only in a densely built city you can achieve the same: people sharing segments of public transit before diverging to a number of different destinations.
In other words, with just a car you can get anywhere you want in the continental US in 2-3 days. With just passenger rail (or commercial air travel, etc.), you can get to passenger terminals in a lot of places, but that’s about it.
I have lived in Phoenix and Tucson, where the light rail is a joke: they are so short and there's only one line, so you probably don't live close enough for them to be useful and they probably don't take you where you want to go. If there was more light rail, more people would use it, but since so few people use it, there is little incentive to grow the light rail.
Contrast Hudson County, NJ, which has a light rail system that's used heavily, the trains are often full during rush hour. You can use it to get pretty much everywhere (except Union City and uptown Jersey City, which both require a long trudge up the Palisades).
For public transportation to work, we first need to make our cities denser. The best way of doing this is by outlawing use-based zoning and moving to form-based zoning. That means getting rid of the concept of a "single family zone" and a "commercial zone", etc. and just specifying stuff about the materials and shapes of buildings. It also means outlawing parking minimums. Many cities around the world (and even a few in the US, re: Philadelphia, NYC) have this kind of zoning which allows for much denser development.
Yup. I live in a metro with the longest light rail system in the US (almost 100 miles) and I don't go anywhere near one during my commute and many don't. It doesn't get half the riders that the second-longest gets. I would not vote for light rail funding...different strokes and all that.