glendalegoon - I hold a UK issued European CPL and FAA PPL, and am used to flying in both environments. (I'm a European instructor also, but of-course have flown with many both UK-CAA and FAA qualified instructors).
The basic requirements in regard of any of the stuff we're talking about are basically identical in both countries, there is no significant difference.
(There are small differences - classifications of airspace and what squawk codes we use - trivia.)
Where I slightly disagree with Jock (who I should also say is a much more experienced instructor than me, so I'll be interested if he disagrees with the way I'm expressing this) is in priorities in the "instructor checkride" (we'd call it a skill test).
Whilst the PRIMARY purpose of the checkride is to establish the ability to teach, there are other matters. The instructor has to ALSO demonstrate a very high standard of airmanship and flying, because they are the example upon which the student is basing their own flying.
In that context, our original poster's failure to know his aeroplane and checklist properly, and be on top of items such as the Tx, checklist, airport procedures and local airspace is in my opinion a clear fail. Presumably that was the opinion of his check pilot as well.
One hopes that the OP, if he's any good, will take all this on board and present himself for his next checkride far better prepared - and then go into his instructing career presenting his students with a much better example than he would otherwise.
Incidentally - it did raise an interesting question. Here in Britain I did my commercial checkride (CPL skill test!) in a complex single - in my case a Piper Arrow IV, and my instructor checkride (CRI skill test) in a C152. An interesting observation that apparently the USA does it the other way around.
G