As a CFI, I check student records and sign the course completion certificate on the PPL application before the student does the test. After the test, I certify the student's logbook. So far, so good, with no bounces from the Belgrano.
A commercial student must present himself for test with a Form 170A, which is, for the uninitiated, is a declaration by an auhorised signatory that the candidate has completed course flying and is, in the signatory's opinion, fit to undertake the test. IMHO, it is a courtesy of the FTO/RTF to extend the same paper cover to the PPL student and FE with the course completion certificate signed off.
So, as an FE, I will take on trust a signed course completion certificate. However, I will want to see a log book and would expect to discuss application paperwork with student and instructor following debrief. The examiner's fee, as BEagle suggests, is not merely for a flight test, but includes time on preparation, briefing, debriefing, admin and travel: which is why FE's are advised by the CAA that no more than 2 Licence Skills tests should be undertaken in one day.
And whilst we are in the subject area..
LOG BOOKS
....are so often scrappy and incomplete, particularly running totals page-to-page and missing exercise numbers / nav turning points etc. FIs should be teaching students how to keep a proper logbook and checking from time to time, shouldn't they? Or are people, as BEagle suggests, taking their (meagre) instructional money and running?