[account42]

> - Apps for IRL services, like getting around (taxi/scooter rental/car sharing), or ordering food, or many other similar things. They get popular because people see their logos around them all the dang time, often together with QR codes with download links. They also often buy ads. Sometimes people recommend them to each other. App stores don't play any significant role for these.

Except if let's say Uber quit the app store then users would still first search there and many of them will install the first result which will now be a competitior since Google is allergic to showing no results if there is no relevant answer.

For everything else there is the issue of trust. Google does everything they can to make installing apps outside the app store feel like you are doing something dangerous.