You're right, I've not lived anywhere with e-tolling. Except London, but they used number plate recognition. WA also uses APNR, but they charge more for it (rip-off).
That MA pass is just nasty.
2012 M3 Convertible, Jerez Black, Fox Red || 27/Aug : placed orded || 2/Nov : Entered production || 15/Nov : Finished production || 16/Nov : At the port waiting loading || 22/Nov : on a boat en-route to the West Coast || 29/Dec : arrives at dealer || 31/Dec : collected it, and loving every second of it since!