It's worse when they /do/ want to be closely involved, but then also thinks that being closely involved means dictating functionality to a T.

Using software does not translate remotely well into /designing/ software. Too many people want to play small-time user interface designer while realistically having no design knowledge beyond "I've used software before, and I have IDEAS about how to do things better."

So much effort is wasted on implementing things people think they need, having recognized a problem and conceived one idea that might solve it if only someone could implement their vision.

I sometimes envision a world where (layperson) patients show up at a hospital with a medical condition, describe a novel surgical treatment to the physicians, and then the physicians follow their instructions exactly because, hey, why not? It might work! There definitely won't be consequences if it doesn't!

Another issue I found while writing software that customer service agents used was we did not get feedback from CS agents without being deliberate, only from the managers of the users (CS agents). The managers were interested in other features like, time tracking, conversion/sales reports, while CS agents were interested (when we finally talked to them) about things that would improve their sales (ex: show available manufacturer rebates for skus to help make a sale)

This is often because people don't understand that the real deliverable is knowledge gained throughout the process and the software is actually an artefact of this knowledge.