A store would have to offer the same cacti sans flowers to gauge their ability to compete with the ones with the flowers. I rarely see any unmolested cacti for sale, but regularly see the glued-flower ones. Basing a business model on duping the clueless should be too embarrassing and bothersome to the conscience to do, yet some people do anyway.
I also do not understand why they don't put a cute little label about enjoying the other plants' borrowed flower, watching it open/close with fluctuations in humidity, until the young cactus can produce some of its' own. With positive & honest spin, they could probably sell even more.
And they could also sell the plants that make the flowers that people seem to love so much.