Because they can only haul 2,000 people per hour, with limited travel lengths and single point termini

A slight modification: though slow, they can have multiple un/loading points. The main gondola at Whistler has a mid-mountain loading point along with a top and bottom un/loading point. The Peak to Peak Gondola only has a loading point at each end because it's crossing a giant chasm.

Your point stands though: gondolas are probably not a great form of transport. That said, I have no idea what the speed limits would be for a gondola that was designed for speed.

They have those unloading points because they are able to take them off of the cable while loading and unloading. We don't design these for cities, but we could. This means loading/unloading could be coordinated across multiple nodes and you could even switch tracks which takes care of the fixed distance problem. Detachable chairlifts can do 12mph which is faster than many city buses. https://en.wikipedia.org/wiki/Detachable_chairlift

Detachable gondolas exist which means you can travel any length you want if you switch cables and have as many terminals as you want.

https://en.wikipedia.org/wiki/Detachable_chairlift

2000 people per hour per direction is a person every 2 seconds per direction which is not that far from a highway with single occupant cars. 1900 per lane is peak, but congestion is much slower. Speed is an issue, but larger gondolas can move more people fairly quickly.

DisneyWorld seem to be planning a gondola-based system for between two parks and two hotels. It is cheaper than extending the mono-rail and probably nicer for all than the usual buses they have.

http://wdwnt.com/blog/2017/04/depth-speculation-disney-world...

Some cities already have them and a lot of new projects are being built too.

http://www.curbed.com/2016/7/25/12248896/urban-gondolas-cabl... http://www.curbed.com/2016/5/19/11714678/urban-cable-austin-...

They are great for getting up a mountainside, but horizontally... they might be too slow. What if we simply speed them up? Maybe too dangerous... but I'd love to see a proof of concept, maybe on a tech campus, and see how it does. I don't see any downside because ski lifts are so damn fun.

Fun is a great reason to do this. Id love to see the Chicago loop from the sky for example.

La Paz actually has a gondola-based commuter system: https://en.wikipedia.org/wiki/Mi_Telef%C3%A9rico

Unique geography there; the city is in a bowl, but El Alto, its main commuter suburb, is on the high plain above the rim of the bowl. There is a single road linking them, which in rush hour is jammed with minibuses.

London also has its "Emirates Air Line", which is a pointless gimmick that doesn't serve a useful route.

They're not really comparable, rail offers far higher passenger capacities and multiple stops are much more practical.

While you can make a multiple stage detachable gondola, every detach point/stage is adding significantly more points of failure and complexity. There is a reason you don't see more than ~3-4 stages and that's it.

They are also very maintenance intensive and not all that reliable.

Rio de Janeiro has these to help people travel around favelas. Really great as they can be installed nearly anywhere and they allow people to travel from point to point without navigating the potentially dangerous streets.

Those have a lot more requirements; capacity and such was already mentioned by others, but things like e.g. wheelchair accessibility is also important.