The downer, of course, is that in all likelihood, the makers of the traffic lights did not design in any kind of solution (neither the heating elements nor any logic to intelligently activate them), and so upgrading will cost tons more money.
Mind you, I'm sure that half the people on Slashdot thought about this sort of thing years ago and expected (if on a subconscious level) this snafu to occur.
Or, if you can somehow detect the snow, you could fully automate it. But doing it purely based on temperature would be wasteful because a lot of the time you have cold without snow.
Lots of lights have nearby cameras (whether for catching people running red lights or for traffic control, I'm not always sure) and perhaps you could use these to detect the snow.
I can't speak for other companies, but my company takes HIPAA very seriously. And I think audits over HIPAA concerns are being taken more seriously across the industry as well.
At the same time, we have millions of lines of code, many dating to well before the days of HIPAA, and if we exposed it all to public scrutiny I'm sure it would make it easier to hack...particularly anywhere a developer was thoughtful enough to mention that in a comment.
The solution of this problem is trivial and is left as an exercise for the reader.