why didn't he just use a cable to pull it? no need for gears, no traction issues, the motor etc can stay stationary. trains have their own power because you can't stretch a cable across the country, but this is so tiny it'd be trivial.
1. The track is curved.
2. One of the design goals was to disrupt the surroundings as little as possible.
This second point is really important, and reveals the utter brilliance of this design. He uses the existing driveway as a second rail, but only for part of the travel. Once the train leaves the driveway there is an actual second rail. I have never seen this before. It is sheer genius IMHO.
Yes, that is possible. But...
> Admittedly would fall foul of requirement #2.
You got it.
There are all kinds of other problems as well. The train will make a very sharp turn every time it hits a pulley. It's hard to attach something to a cable in such a way that it can reliably go over a pulley. Yada yada yada.
Here's a really cool example: https://en.wikipedia.org/wiki/London_and_Blackwall_Railway#C...
And they can go around corners: http://www.cablecarmuseum.org/archive/Anat/Anat.html
It's a lot harder to go around a corner without some kind of guidance for the wheels.