They have, trouble is if you wipe out the navigation cluster and/or the electrics fail you're rooted. The road book holder, though motorised, retains the manual wind on capability so you can still follow the route. That's also why they still use the self contained ICO odos. They're are virtually indestructible and self powered. I was surprised last year when I dug out a >20 year old unit from underneath the workbench at home and it turned on. I was even more surprised at the amount of interest in it when I put it on ebay. A guy from Israel ended up buying it.