Does the Apple Store have refunds? If a user could refund an app within 48 hours of purchase (no questions asked), might that increase sales? (An abrupt change in policy might negatively impact premium "one time use" apps though...)
I reckon trying to solve this as though it's rationally thought-out is wrongheaded. I didn't consider and decide that I didn't like paying for apps, I just got used to not paying for apps. And indeed, once I got used to paying for apps again,* I stopped worrying about whether the $1 app would actually do what I wanted.
* Since we're sort of discussing what would prompt people to spend money, for me it was games. Free-to-play games are so reliably so annoying that I eventually swore off downloading them.
On that same note, I’ve never asked a decent restaurant for a refund or exchange of a bad food or drink and not received it either.