All they need is inspectors on motorbikes riding between cars that are stopped at traffic lights.
Large number of people are using their phones when waiting at the lights.
A motorbike inspector riding between cars would make an infinite number of catches.
In my mind, I'd rather people check their phone at a stopped traffic light, going 0kph; then while driving at 100kph or turning etc...
Ultimately tickets should have a purpose - prevent the most atrocious behaviour we see.
There's a poorly marked off-ramp from a major freeway in Toronto; and after off-ramp it's still a divided highway that basically looks like freeway. Cops are constantly staking out this exit because they know they'll get tickets - but what are you teaching? Most of these people were honestly trying to do the relatively right thing. There's no lesson or behaviour modification, just income. (if you want to modify behaviour at that particular offramp, add signing and/or lights etc).
Understanding that it's against the law in most places (because technically you are "operating a motor vehicle", I honestly don't have a problem with people glancing at their phone on a red traffic light. Others, I suppose, may vehemently disagree.