I don't fully understand the coin-operated part yet! Is it like a shopping trolley where you get the coin back at the end? And does anything stop someone else coming and unlock it? Or do you use your existing lock to tie it to this cable?

I certainly prefer these to the hanger racks. Those are just awful and add so much stress, especially when you join the train in the middle of a route, people are milling around, and you're trying to jam this bike into a really awkward space while people stream past you. I actively avoid taking my bike on those routes because it's so stressful, the strap/bungee alternatives are much better.

Oh, such an interesting rack-lock! I avoid using hanger racks if possible, also because I have rather broad handlebars and the hanger racks on the trains I use often are rather closely spaced. So I prefer to lean the bike, however with my U-lock it is almost impossible to lock it to something (which is a good idea if I don't sit close, although I haven't heard of a bike theft on the trains here in Slovenia yet).