I would buy much more if I could try for a few days. I don’t understand why they can’t do this. Or better, they can, but don’t want to. This is outright user hostile.
Talk to your app maker, not Apple. Apple started allowing free trials last year:
"Non-subscription apps may offer a free time-based trial period before presenting a full unlock option by setting up a Non-Consumable IAP item at Price Tier 0 that follows the naming convention: “XX-day Trial.” Prior to the start of the trial, your app must clearly identify its duration, the content or services that will no longer be accessible when the trial ends, and any downstream charges the user would need to pay for full functionality."
https://developer.apple.com/app-store/review/guidelines/#pay...