To ignore misuse of the cards is ridiculous!  How can it be passed over, except in cases of proven error or mistakes?  There is no excuse for people who spend the city's (people's) funds on personal items and/or services.  Intentional misappropriation should have one result--bye, bye thief.
And yes--our mayor should condemn such stealing and deal with it; that is part of the administrative duties of any mayor's administration.