Re: I'm failing to see how this is Just Eat's fault
The only way that they could reduce this happening is to create an app that would SMS/call the client without divulging the number to the driver and instead of passing the phone number with the order to the restaurant give a PIN to enter into the application. If the person responds back then they give away their phone number. Of course there'd be no way to hide the name and address though they could just pass along the first name and only show the full name in the app if the driver can't find the place. Once it's delivered, by having the customer sign or tap a button on the app then the details can't be shown to the delivery person.
But you are creating a system in which every delivery person would have to sign up for the app or be registered by the restaurant. It's an extra step and wouldn't always stop this problem, just reduce it.