Traffic Laws and the Immigration Question

An MoJ reader comments on the Vatican's new Guidelines for the Pastoral Care of the Road:

It seems to me that the document restates traditional Catholic teaching on obedience to the positive laws, but I wonder whether that teaching takes proper account of the difference between civil and criminal codes, and more specifically the functionality of laws designed to encourage rather than to coerce absolutely.  One might analogize to laws which would tax pollution, permitting companies to buy the right to pollute from cleaner factories (thus creating an economic incentive to build cleaner factories).  On the one hand, one could say that pollution is immoral and wrong in all cases; but on the other hand, we all pollute somewhat (esp. if CO2 is pollution), and that type of law would shift from a punitive approach to an incentive approach. 

It seems to me that speed limits for automobiles are functionally similar.  We know that we can go a little above the speed limit safely, but the risk of substantial fines deters us from speeding very much.  It is quite possible to imagine a detector placed in the license plate, with monitors around the interstate highways of a state, so that the state could calculate the driver's rate of speed all the time, and fine you accordingly, sending a bill to your address every month (or perhaps automatically deducting it from your bank account).  If we conceptualize speeding in this way, I wonder whether it's fair to say that any excess of the speed limit is per se wrong.

Of course, the circumstance of someone driving recklessly, or unsafely, or drunk, is something else.  That seems to be a direct violation of the obligation of charity, whereas the simple violation of a speed limit is only a violation against charity inasmuch as the positive law requires a limit which is safe.  (E.g., Congress used to require a 55mph speed limit even on I-80 through Nebraska.) I suppose following the speed limit would be a prophylactic protection, if I might use that phrase, of the obligation of charity, but not a direct requirement.

I analogize to immigration, because it seems to me that immigration violations are substantially similar to speeding violations.  They violate the positive law, but in many if not most cases, would implicate immorality only to the extent that it's immoral to violate the positive law.  Of course, the main question with regard to illegal immigration is whether the punishment fits the crime; but it seems to me that the moral status of the violation may be relevant to that consideration.