One of the things that sound mixers have to deal with is shoe noises. Sometimes, the shoes that make actors look super sexy also make a godawful amount of noise on hard floors.
If the actors’ feet aren’t going to be in frame, then usually the sound folks just put down matting (it’s rubber matting with all-weather carpet on one side) on the floor, or have the actors wear slippers instead of regular shoes, but if the camera sees the floor then that’s obviously not an option.
Usually, then they’ll pad the bottoms of the shoes so they don’t make noise, but high heels can really be a problem – normally I’ve seen them put tape on the heels of high heels, but that can ruin the shoe (and don’t think they’re not going to sell these at the end of the show). Hence, the little crutch tips, which I think are hilarious and very cool.