Card numbers just work.
Also, payment "apps" that pack their own web engine and need 300-500 megs D/L, plus refuse to run on rooted / "unvetted" systems. No fucks given! Go away, give a browser and numbers.
Unfortunately you still can't easily distinguish between normal browsing and private browsing that way (though browsers could implement that in theory), but I ran that setup for a while back when Firefox couldn't integrate with the App Tabs or whatever it's called where Android apps have their own minimal UI around a full screen web view (which used to always be Chrome).
Card numbers don't work because the business receiving the payment doesn't automatically get a signal from the bank when payments come in without an annoyingly complicated banking integration, which is exactly what these new services intend to solve. They do work for the consumer in some cases, and I have been paying for some online services with regular old bank transfers in cases where I didn't need a payment to go through the same day. That doesn't mean it's an equivalent system in most cases.
If your banking app doesn't run on your device because of something as silly as root detection, you should find a better bank.