Per my other comment, look-down phone detection cameras are becoming broadly available, and my local police occasionally use raised vehicles like mini-bus with

Per my other comment, look-down phone detection cameras are becoming broadly available, and my local police occasionally use raised vehicles like mini-bus with plain-clothes officers looking down into cars in the adjacent lanes then dispatch mobile units to pull over and ticket the offending drivers. It is possible to enforce, and ML-powered traffic cameras are only becoming more common