1) What do we want people to do?
2) How do we get them to do it?
The answer to 2 should always be simply explaining the reasoning for 1, even if it would be a little less effective than making up some lie. In the long run this builds trust in the government, instead of reducing it leading to a total breakdown of compliance because they lie all the time.
The most dangerous and insidious thing about this dynamic, IMHO, is that a certain type of smart or self-identified elite person will go along with it, because they, too, believe that you can't just tell the truth to the general public (of which they don't consider themselves a part of course).