It's Gotta Be The Shoes

So this person appears to be dressed at least somewhat professionally. At least I think she looks dressed up a bit, but at the same time I'm a guy, so I don't know the idiosyncrasies of dressing up (in fact most of my outfits wouldn't match if my wife didn't pick them out for me). Anyway, it looks like she's wearing flip flops. So what's going on here? Does she have another pair of shoes in her bag that possibly has heels and she's wearing the flips because they're easier to get around in and more comfortable, or do the flip flops type shoes really constitute business appropriate shoes? And why am I looking at this picture and noticing shoes? What's up with that?

For the detail minded, I snapped this out on the mall in downtown DC around midday. There was a solar power housing exhibit on the mall at the time and that's what you see in the background.