Whilst I acknowledge your frustrations about the recent MoT failure, as they say "Rules is rules".
It's all a matter of exactly what condition the vehicle is in when it's presented for test. Strictly speaking, the tester could have filled the washer bottle for your mate, or put a tie-wrap on the brake pipe for you, but in both cases that would have constituted a "repair" resulting in a refusal to test (fail), the repair and then would have elicited a retest fee.
I have an arrangement with my MoT tester that he does repair and retest without consulting me everytime, and will do the repairs unless the prices start getting silly.