LA traffic versus UK traffic

Community question: What is the correct amount of time to wait before tooting at someone after they have ignored a traffic light turning green? 

 I’ve had people toot me a nanosecond after the light has turned – before the synapses in my brain have even had the chance to bond together to tell my foot to move onto the gas pedal.  I tend to wait a little longer than that.  In fact my English sensibilities are such that I’d probably wait till the light changed back to red again before I ever tooted anyone.  But as I know I’ll just get tooted for not tooting I give ‘em a good few hearty seconds before I start sounding the horn.

It wouldn’t happen in England.  Someone would have had to pass away at the wheel before they got tooted for not moving on.  The driver in the car behind the deceased would just sit muttering passive aggressive threats under their breath for about an hour and eventually just give up and drive around them…