I think the Ford/GM thing of using the brake lights also as the turn signal is far more dangerous -- when the brakes are on, a turn signal just turns the single light off. In traffic stopping quickly, and you can only see one light, you have a fraction of a second to determine if the car is stopping or changing lanes.
I see this in traffic all the time, and nearly been hit by cars that look like they are braking but actually changing lanes. Why are separate light colors not mandated?
They are mandated in any country that uses UNECE regulations for vehicle lighting. In the US and Canada, red turn signals are allowed as a cost saving measure. That's why you can see high end luxury cars with LED tail lamp clusters that have red rear turn signals in the US.
I see this in traffic all the time, and nearly been hit by cars that look like they are braking but actually changing lanes. Why are separate light colors not mandated?