Why not headlamps? Cadillac using LEDs for headlamps. As well as I believe BMW and Audi/VW.
LEDs also light faster, which grabs your attention better. But it still doesn't help when the moron in front of you hits the brakes every time a leaf blows across the road in front of him.
Yes, LEDs will snow over faster in winter. But a standard bulb will, too. I've even had my headlights (sealed beam and 9004s) ice over. How many watts does the light in a street lamp run? That's all that's needed to keep them clean, and really, only for a few days a year. With computer-controlled traffic lights, most towns/cities can activate them when needed and still save a bundle.
The trouble with LED street lights, is they can be seen too far away. There is a (LED) light on route 6 near Bryan, Ohio, that can be seen for up to 15 miles away. There are a lot of wrecks from people blowing the red light there, too. The light really sneaks up on you. But that seems to be a problem with any light that can be seen from a mile or more away, without a lowered speed limit in front of it.
Why run the old socket/bulb style trailer lights? The 4" round bulbs have the same plug as LEDs.