Continuing on the example - a flower shop probably manages their inventory via spreadsheets. They're not happy with it, but I doubt they'll fork out $600/year for an inventory tracking app. And I think it'll be very hard for me to get in touch with flower shop owners to validate the idea - they live in a very different world to mine. So the only path to success is to publish an app on the Apple App Store and hope it takes off.
That's similar to what I ended up doing with the last startup project I had, unfortunately it didn't work out.