"There are only 10 types of people in the world:
Those who understand binary, and those that don't."
LOL! I just noticed!
I think that in this case, ignorance may not be relevant, unless there is a written statement somewhere (innaccessible, probably) that would require one to signify a change of address to both states.
As with a lot of law changes, there's usually an adaptation period: old timers don't change their habits too quickly. So it falls down to law enforcement to make a judgement call, right there, on the streets. Not good.
Now if there was a way for the state/country to communicate something to all of its citizens, cheaply, and assuredly... oh but wait, that would require a communication infrastructure
I say give everyone a citizen login ID and internet access. Power to the people!