What are the challenges for software testing?

also a real interview question. I have listed several ones, but there are not very good.

1. UI automation test, android 5 upgrade t 6, lots of widgets and elements id need to be revised.
2. Always testing should be under time constraint 周末加班，或者紧急加入之前测试的
3. Understanding the requirements 比如tethered data 2, 3 每一个手机不一样
4. Application should be stable enough to be tested 刚出厂的不稳定
5. Setting priorities for testing 同时要due的
6. Requirements changing 与过去测试不一样的app细节
7. Lack of tools, resource, and training 比如缺少测试apk，以前的不支持了
8. Test Coverage