First of all, this particular WPA project wasn't silly, it was an effort to inform the American public of the poverty in the Midwest brought about by the Dust Bowl and therefore show the importance of the New Deal, which is why it is different from the Jerusalem of hipsters putting the TMNT on a manhole cover.

Second of all, the WPA was an effort to get every able-bodied American to work to revive the faltering American economy which, I reiterate, is quite distinct from a piece of government-sanctioned fanart.