Cheaper and easier to build. Apple's SDK offers a lot of options and doesn't require a lot of credit card details, unlike some of Google's APIs.

Plus, web apps are gimped on iOS (no notification support without going through a cumbersome PWA installation flow and data getting wiped every 14 days if you're just letting it run in the background).

For one users don't have to say they consent to data extraction as often, and some people don't use web sites very much.

It can monitor your location and notify you about nearby reports.