And how is this helpful? Is this a solution? What if the app-in-question was a different one? Not using Instagram at that would be very helpful, indeed...
Actually, we do. It's called democracy and how laws are made that companies have to adhere to.
While that's an entire different scale as "didn't display cookie banner" the mechanisms are the same and in place. If the EU finds privacy infringement important enough the infringer will be warned than fined[1]. I'm no lawyer, but I would expect that when a company doesn't pay that fine, they'll ultimately be prohibited from doing any business in the EU. e.g. through blocks, frozen accounts and such.
[1] https://commission.europa.eu/law/law-topic/data-protection/r...
The key point here being "comply with". "Let me track you or you can't use this", confusing or coercive "consent" dialogs etc. don't comply.