I've had on pretty much everything except pj's or an evening gown. Depends on what I've been doing prior to heading to the polling place.
OK .... I suppose I would have to also qualify the above to state I have also not worn a wedding dress nor my "birthday suit" to vote, either.
In regards the photo: A nice looking couple they are, and I see that the others behind them (at least one of the five appears to probably be an "official" of some sort such as security guard) are also dressed nicely. I also noticed that there are ribbons/streamers above the entryway, which says to me that this is something considered a celebration for those preparing for this and for those entering. It appears the folks being photographed are pleased/happy. A good occasion - one that they may have felt appropriate for "dressing up."