This is what I think is going on: car companies (including Toyota) are NOT in the business of manufacturing GPS equipment. So they have to outsource the navi system to third parties (Alpine, Delphi, Denso and others).
The GPS equipment manufacturing companies are likely to have products with many features, however the car manufacturers are primarily looking for a product that can do the navigation but is not very expensive (they rather keep the profit than passing it on to a third party). So the GPS companies offer them a stripped version of their best products and we (the buyers of the vehicles) are likely not to know any better since we presume that since it came with the car, and it has a big screen and nice colors it has to be best out there. I bet many consumers think that the OEM nav systems in these cars are tops. We are being duped!