And those “reasons” were plentiful. Most importantly is their market share. From a purely business perspective, if a distributor has 200% more users and charges 100% more while offering the same features, they will be the better choice - purely from en economical perspective. 30% is ok because you will reach a larger audience and if so many publishers disagreed with Steam’s cut, they wouldnt all come crawlin’ back would they? In other words, the market dictates the price and the market has decided that price is 30%. It doesnt matter who does or doesnt defend it. Thats what it is.
Your app has a button on its front page. No one ever presses that button. With good telemetry, you will know this and remove the button. The only thing you need to know is how many times each user opens the app and how many times they tapped that button. Crash reports can include the causes of errors. Without this data the app might have that unused button there forever and crash everytime anyone taps the donate button and you wouldnt know why you arent getting any dontaions.
Telemetry is usually collected on non metered networks. Usually it is opt-out by default, set by the user in the apps settings. Personally, I’d inform the user of this and let them decice on first startup.