I feel like women wearing yoga pants all the time now is a trap. Here you are, just walking with your wife shopping when a lady walks by wearing yoga pants and a thong underneath. You can tell it's a thong because there is no panty line except at the top of their buttcrack.
So women have a coordinated attack effort. Your wife is watching you to see if you look at the yoga-clad buttocks. The lady wearing the yoga/thong combo knows it will get attention and it will make you look. In the words of Admiral Ackbar, "It's a trap!"