Technically it is in breach of guidelines/terms & conditions applying to each store, but either they don't have or don't wish to expend the resources in checkin

Technically it is in breach of guidelines/terms & conditions applying to each store, but either they don't have or don't wish to expend the resources in checking each and every app. This approach would also potentially mean that they would lose the protection of the DMCA which in their position as hosts of content, rather than providers, means will only be liable for copyright infringement if they do not respond to a takedown request. If they vetted each and every app and one slipped through which the store holder should have rejected as being an infringement then they would potentially become liable. As a result, the onus is on IP owners to contact the stores to request takedowns. Unless an IP owner is actively scouring the stores, this may result in copycat apps remaining up. Yes, it may degrade quality, but this is preferable to the above alternative.