For starters, how many of those other provinces and states have transit signals that have a red, yellow
and green light just like the vehicle signals? Because they all seem to set up their lights quite differently from Ontario. For all I know, the lights for the Edmonton LRT don't use circular red or yellow lights either.
Wanting retesting to come with license renewal isn't a good reason to keep using standard red-yellow-green signal lenses for every signal head. Worded signs take longer for people to process than symbols and add extra clutter to roads. Maybe back when transit and right turn signals were rare and virtually every signal setup that had dedicated signals for a different movement looked like
this, this worked fine. But now, transit signals and dedicated right turn signals are popping up all over the place. And are people getting them mixed up?
It seems like in London, that was actually a problem when the BRT opened. And you know that the King St setup is a whole other monster. My point is that regardless of anything else, if you need to a bunch of signs to distinguish each signal, that is flawed design. This isn't an argument against retesting BTW, it's an argument to allow better transit signals and red arrows in Ontario.