The issue is not having a default app or not, the issue is having a qr reader external service. Imagine you are an app developer of a really simple app that ta

The issue is not having a default app or not, the issue is having a qr reader external service. Imagine you are an app developer of a really simple app that takes a number and tells you if that number is in a valid phone format or not. You have a textbox, the user enters it, you do the checking and display the result. Easy. Now imagine you want to allow scanning a qr which contains a number, to do the checking afterwards. You need to either ask your users to use an external app to scan and then open yours, include all the qr related library inside yours, or use a special intent from a third party app (that the users need to have already installed). First solution is slow and inconvenience for users, the second is what almost all apps do, but then the code logic is duplicated on all of them (with the increment in app size). The third option is the best, both for the developer and for the user, however there is no official qr service so in the end this is basically option 1. I mean, you already have a service to get a picture, a file and a contact, among others (you don't need to include all the code, simply do a call to the respective intent and wait for the result) so why don't extend this with the qr too?