that's just a not-so-subtle marketing tactic.
Why are there slow lanes for people with less money in a government situation?
Can you pay extra to skip the line at the DMV? (actually, you can in California, by having a AAA membership)
To the question for government agencies to market they services, I absolutely think they should. Often marketing it's just informing people that something exist, so if they government wants people to use some service or change their behavior, they should do marketing.