alt Hacker News> I'm pretty sure that simple switch is something directly in the circuit for the fog light, and there is a dedicated wire between the fog light, the switch, and the fuse box. And if its an old Jag, those wires flake out and have to be redone at great expense.
I don't really want to get into a big debate about this as I haven't worked on Jags, but I don't believe that replacing parts of the loom is would be that expensive. Remaking an entire loom, I will admit that would expensive as that would be a custom job with a lot of labour.
> Compare this to the databus that is used in today's cars, it really isn't even a fair comparison on cost (you don't have to have 100 wires running through different places in your car, just one bus to 100 things and signal is separated from power).
Ok fine. But the discussion was button vs touch screens and there is nothing preventing buttons being used with the newer databus design. I am pretty sure older BMWs, Mercs etc worked this way.
They can be used, they just need more complexity than a simple switch that completes a circuit, they now have tiny cpus so they can signal the bus correctly. The switch must broadcast turn thing on when the switch is set to on, and then turn thing off when the switch is set to off, all with whatever serial protocol being used (including back off and retry, etc. ..). So your input devices need to be little computers so that you can use one bus for everything, now you can see where one touch screen begins to save money.