In regards to evaluation a checkride says that on a particular day, with a particular examiner, and a particular set of environmental circumstances you met the standard at that time or did not. An examiner gets a fraction of a snapshot to determine a pass or fail.

Years ago, I was in favor of eliminating the DPE system and allowing instructors of a certain experience level to "self certify" the applicant. In other words, I've spend 40+ hours with this person, and I'm in the best position to judge competency. Not a DPE who may or may not have a financial conflict of interest. Never worked out the kinks in this but my belief is the applicants would actually improve as the CFI is "on the hook."

As a side note, when I took my CFI initial in 1991 in the Detroit FSDO all applicants for CFI initial were required to test with the FAA. The DTW FSDO would not allow DPEs to do the exam (that has subsequently changed). Although the failure rate was high, it was not impossible to successfully complete a CFI initial with the FAA (case in point).