Integrated sat nav
"Why do people pay £500-£1000 for such an poor option when a £80 TomTom or the free Nokia Here app will do a far better job?"
They're often worse than that - £1000 - £1500 for the integrated sat-nav is a massive rip-off and I wouldn't opt for it if I bought new. But if you don't buy new then it's a handy thing to have in a used car where the cost doesn't filter through to you so badly.
They go out of date but 95% of the time they're fine, and the extra time spent programming a destination into a possibly badly designed one is saved not having to plug in the tomtom to the windscreen and have cables hanging around the dash.
And more time saved when you stop for a quick pee at the services and don't have to unplug the tomtom every time.