Camera-only tolls are the wave of the future. From Connecticut going north, toll booths with actual people are becoming non-existent. It does make for faster and easier driving, as you don't have to worry about traffic backups at tolls and whether or not you have the money.
How the photo-tolls bill out-of-country drivers I don't know. As previously mentioned, most of the photo tolls and speed traps are considered minor violations, so agencies may not bother spending time on going after out of country vehicles. BUT.... in today's world, everything is tracked by computer! Sure, you can ignore that toll bill / speed trap ticket, but the information is kept and possibly years down the road an old ticket may come back to haunt you.