Failed for Going <10kmh Under the Speed Limit?

Just did my test in Kilkenny, I got 6 grade 2's for progression, the tester explained to me that I can't be sitting at 42/43kmh~ in a 50kmh zone. To me this is unfair, the roads which I was marked on had houses on either side, lots of traffic, unfamiliar road and people out walking. Just wondering what other people think of this, and if they have experienced something similar.

Time to hunt for more cancellations....and drive faster.

EDIT: woah this is at the top of controversial this week lol, thanks for everyones input, all the best for anyone doing their test xx

EDIT 2: ok so to clear up:

I chose to go slower in these residential areas for my own piece of mind, not in an attempt to show the examiner i was being extra cautious.

i did not hold up any traffic in these 50 zones because of going 6/7kmh under the limit, the only instance there was a xc90 tailgating me when i was hovering around the 46/47kmh mark in a 50.

ive never had an issue with progression in my EDT lessons, my instructor was shocked when i showed him the progression marks. ive had my fair share of shit running out into the road infront of me, so unless i know that area, im going to be a little bit cautious.

I appreciate your guys' advice and taking the time to share your experiences, ive taken note of a good few bits of your advice. thanks :)