Where can I get fitted sheets for mattresses that are not super-thick? Fitted sheets these days seem to be made only for very thick mattresses, so that they will slide around and bunch up on thinner mattresses. I have heard you can buy mattress garters to make them fit tighter, but that these do not stay on very well.
If I were into plots, I would say that the mattress makers have bribed the sheet makers to not make sheets for thinner mattresses, so that people will have to buy new, thicker mattresses in order to be able to get fitted sheets that really fit.
There is a real unmet need here, sheet makers, and you do not seem to be competing to fill it. We have an inexplicable and bewildering failure of the free market to function as it should. How can such a thing happen?