FE's have only been "trained" since we adopted the JARs, prior to that you needed a lot more instructional experience and IIRC a couple of good reports from your FI rating tests. Nowadays, all you need is 1000TT and a pathetic 250 instructional. As far as relative experience goes to examine someone, that's not much better than your 225hr FI(R) for the hour with an instructor is it? We do however have a "standardisation" flight test every three years or so.
Whether there's much merit in just putting someone in an aeroplane for an hour with an instructor, or if it should be a mandatory test with an examiner, is a different question. What I'm saying is we all regularly examine or assess (what's the difference practically?) the people we fly with, it's part of the job. A lot of the time, yes it may have no legal standing, but we still do it.