I recently learned about an app called "Too Good To Go", which lets you buy food that's close to expiry at a discount, to help reduce food waste.
Problem: it's only an app. There's no web interface whatsoever.
This means you have to download the app not just to place an order, but also to see what restaurants are on it and what they charge for the discounted food - basically to find out whether it even has the possibility to be useful to you!
This is an accessibility issue for some people (browsers can be more easily customized with accessibility tools), a pain point for me personally (whenever I'm ordering food I'm already at a computer, so having to dig out a smaller, less user-friendly device is an additional layer of inconvenience), and also makes me suspicious.
Generally, when companies try to push you towards an app for something that can easily be done with a website, it's because they're trying to collect user data or prevent users from blocking ads or tracking.
Given that everywhere I order food from has a web interface, I can't imagine any technical reason why this would need to be app only. Which makes me wonder if there's an ulterior motive.
Even if there is some technical reason why Too Good To Go wouldn't be able to make a web interface, they should at least let participating restaurants include Too Good To Go bags on their own online ordering web interfaces, so existing customers don't have to switch devices to take advantage of this very useful initiative!