The problem is that most normal people (HN is not normal - mostly for the better) don't even understand what sideloading is - let alone actually care.
How can we fix this?
(aside from making people care - apathy enables so many political problems in the current age, but it's such a huge problem that this definitely isn't going to be the impetus to fix it)
Every time you have to clarify, it’s another opportunity to lose the asker. It’s not a good strategy to use a term we have to keep defining or that people may misunderstand. Stallman and the FSF continue to make that mistake and we have had decades to understand that’s a bad approach.
Call it something else, like a “direct install” or something better. You can still have a deeper meaning to it (“direct because it bypasses the App Store middleman”) but make it something people can understand fast. You can’t fight marketing with ideology alone, you have to beat them at their own game.