Quite frequently - they even get a language review. They must be in a specified format in terms of punctuation, etc. I can tell you that the UK person was very proactive and quite correct in everything he said. His checking was certainly detailed, but others are definitely not so good. As with TREs, there is no consistency, which is one thing you can admire Transport Canada for.
It's a good point you make about authorities - I have no answer to that one. I've heard nothing from our students with the IAA either, or from our Dutch guys. As the saying goes, I couldn't possibly comment.
Phil