West Ham Online

Yes. There are many tiers to 'mexia training' so if you do the full suite of coaching licenses, you also do the full progression of media training. Each module builds upon the modules completed to date so once you've done the lot, each fully-qualified coach has undertaken the exact same set of media training modules which explains why they all sound similar. When they're using deflection and you don't quite understand what they're saying, that's the point at which you notice that they're talking in the same way as the last coach you didn't understand.

We don't really pay attention to coaches' press conferences outside of who we support but you can look at a few on YouTube, especially if you look at similar managerial positions like an under-pressure boss on a losing streak having just lost again, and you'll recognise very similar platitudes throughout. 
In sport, you get a more broad licensing authority the higher you progress so you get UK qualifications, then UEFA (Europe) then FIFA (world) awards which explains why top-level coaches rattle off the same old nonsense no matter where they are from in similar situations, both positive and negative.

It's training, and if you defer from the training, it looks like an angry rant (Postecogliu) or inane gushing (Holloway) we all laugh. Nobody wants to be laughed at, so we revert to the training. It takes years to become fully-qualified so it's driven into you.

Politicians are the same and to a degree, journalists, which is why similar questions are always asked.

So true. What is it that makes them do that? Genuinely, do they get taught it at the UEFA/FA courses these days? With a few exceptions, they all talk in circles.