Automatic windscreen washer

I'm a bit bored with those silly buggers who charge over to you at the traffic lights and ask you if you want your window washing while squirting what looks like last nights bong water all over your car and then smearing it with an old t-shirt all over the place. Then when you say 'no, piss off and get a job', the get all arsey with you and then go an' hassle the next victim. I propose a system of hydraulically operated arms and squirters, positioned on the traffic light poles that, when the lights are on red, come down and automatically wash and dry the windscreen of the first car in the queue. All the technology is availiable, and you wouldn't have to spend 10 minutes cleaning bong water off your paintwork. Every so often you would find yourself at the front of a queue, and get a nice clean window. Just one of those little things that would make living in a city a more pleasant experience.