I'm not sure I entirely agree that it's not a tricky subject (it seems like date bugs show up pretty often in computing and there are a pretty good number of corner cases, plus complications from things like time zones) but it most definitely should not be allowed to happen and it sounds like they need to throw much heavier testing resources at it. As another poster mentioned, this is an issue that messes with people's trust in these very personal devices.

As long as humans are writing the code, there will be cut corners and missed test cases. The attitude the "this is easy" could have been the reason it happened in the first place.

If date and timezone related code seems simple/easy to you then you're using libraries! It's messy and easy to mess up!