I think there are really obvious reasons for ridesharing and taxi apps to exclusively use apps. Notifications are very important to the experience (which you can't do on iOS Safari). Having persistent location access like a navigation app is another key part of the system.
Don't like it? Put your arm up and hail a cab or call the dispatch office to request a ride, that's what we had to do not even 20 years ago.
The app store duopoly and privacy problem isn't one that's solved by playing whack-a-mole with individual companies on those platforms. The way to solve those problems is by regulating Google and Apple's App Stores for both privacy and business practices.