The cases you cite are the exceptional cases and not the normal cases. There is a little bit of overlap in what some engineers and some engineering technicians do, but there are a lot of jobs (most of them) in both fields that can’t be filled by the other group.
What about in the UK, Ireland and Hong Kong?
See my reply in the other thread: http://talk.qa.collegeconfidential.com/discussion/comment/21765760/#Comment_21765760