> Would such a system (and automated enforcement) be OK?

Yes. But as you pointed out, `automated enforcement via a fine, without knowing the identity of the perpetrator` is hard.

And as others have pointed out, Point 1 and Point 3 are also difficult to accomplish.

Question for you is, are you okay for the government to roll out a mechanism to detect and prosecute people changing lanes without giving you any guarantee of respecting the 3 points you mentioned above?

If your answer is no, you are not okay with it, then we are all on the same side.

If your answer is yes, then you should read the article above by moxie (very interesting article)