I think the UK also has non-toll exits (I think every country with a developed highway network does?). The obvious solution is just to put the cameras on the n

I think the UK also has non-toll exits (I think every country with a developed highway network does?). The obvious solution is just to put the cameras on the non-toll exits as well. They tend to be spaced generously on US interstates, so it probably wouldn't be a significant expense relative to the overall cost.