Customers do not value quality
If customers would drop apps that are of bad quality and explicitly request the results of quality assurance test runs we all would not have this discussion. Does anyone ask any software vendor to show the the test results as condition of buying an app? It doesn't matter if it is a 99 cent app or an enterprise suite, as long as customers do not value (means pay for) and demand quality we will continue suffering from bad apps with security holes. So unless you start asking for what you want stop complaining about it.
I work in QA for over 15 years now and it is odd that so far only one customer out of thousands asked to see test plans and test results. I have no problem sharing my results and would appreciate if customers challenged me on my test approach. It would make things better for everyone.
I also noticed that with the Agile wave coming over software development we get releases much faster with more features, but with less and less quality. Sure, even before Agile apps had bugs and security holes, but then it was development driving releases, not some product owner with arbitrary release dates and a far to big wish list as backlog. Devs get the time they need, QA gets the afternoon before release. So you want "working software" as the Agile Manifesto claims is more valued? Then stop this madness and put more effort into fixing bugs and less effort into cramming more and more half-baked and untested features into releases.