These things happen unfortunately. I don’t rate every hotel I stay at, every restaurant I eat at, and every item I buy from Amazon. Im assuming most people dont. Buying, downloading and using the item is the main priority… rating it is rarely going to be at the forefront of their minds.
Not really sure there’s much that can be done about that. I know there was a trial when they sent out emails to remind buyers… but in the month previously I’d bought about fifty items and the fifty emails weren’t exactly welcomed!