Because this relies on either odometer readings, which, at least here in the US, you wouldn't be able to say how many miles were driven in one state vs the next. Or it would rely on tracking the location of the vehicle, which is downright creepy and sets off all kinds of alarm bells in people.
There are no more toll booths in the state of Massachusetts.
If you travel on a toll road in Massachusetts, your car will be tracked either by E-ZPass transponder, if you opt in to that system (at a substantial discount), or via photographing the license plate and sending you a bill in the mail.
Also, pretty much everyone I know, even the most privacy conscious, carry a tracking device in their pockets at all times. I think that rms may be the only person I've met who I know does not.