I think that the issue is when you have an Android/iOS/Windows phone, it is clear that it is a 'phone', i.e. it is a separate unit that looks like a phone, and it is therefore clear to both the drivers and police when the driver holds or taps into the phone (other than to make phone calls or use the SatNav).
But when the unit is installed where the radio would normally fit, the borders are blurred and drivers feel that it is 'OK' because it is part of the car, like radio, or CD player, or factory-fitted SatNav.
It is definitely impossible to enforce, because the Police can not see that the driver is doing something he or she shouldn't be doing, not even if they stop the driver - unlike phone calls or text messages, playing around with the system does not leave a log that is easy to trace (checking the browsing log at the ISP based on the ISP 3g/4g records is anything but trivial and is only likely to be applied in case of a fatal crash).
The combination of the 'it's OK because it's part of the car just like a radio' feeling and the very low risk of getting caught is likely to trip many drivers and have a negative effect on road safety.
I think that the car industry should have a serious discussion regrading what is acceptable and what is not. The old restrictions prohibiting holding the handset or sending/receiving text messages is out of date, with people using Twitter, Instagram, Facebook, Email, or just Googling at the wheel.
The reality is that people just do this... saying it is wrong won't change it. I think the industry will have to come up with an ISO or DIN or BSI standard for 'mobile data interface to be used in automobiles' or such like, based on ergonomic research, detailing which features are allowed and which are not, and fitting any device that is not certified (or has been tempered with) will be illegal.
At current manufacturers just make it up as they go, from BMW iDrive to MB COMAND and Linguatronic etc etc....