Think this is an Mot fail? Oh no!

Bought my M59 in March, just after it had a new Mot. It's a 2008 model.
The brakes felt reasonable, but nowhere near as good as my B9, so they were on my list of jobs to look at. I had no real worries - after all, it had recently passed its Mot and had only covered 1600 miles since.
Yesterday, the car began jumping around every time I braked, so I gingerly got it home, stripped out the front brakes,  and this is what I found:


Some Mot! The pedal probably felt firm to the tester, but obviously the brakes hadn't been looked at. That is about the worst I've ever seen on front discs. Both discs have reasonable wear on one side, but the other side has never seen a pad, and just looks totally shot.

As it's the inner side of each disc, I suspected stuck or stiff calipers in their carrier, so as they were already removed, I began stripping the carriers down. Yes, there was a little stiffness, but I could slide them in and out without much effort. The pads were in poor shape, with the backing separated form one pad each side, and uneven wear as you would expect, given the disc condition. Like so:


So I've ordered new discs and pads from ECP, and they should arrive today. They had a 50% discount offer going (still in play until midnight, if anyone wants brake parts) and I got the lot for just £33.

My concern is this - Is this a known weakness on the M59, or a one-off?
I suspect it's a one-off. There was a bit of bodgery present, because there were odd disc securing set-screws on one side and none at all on the other side. I had to re-tap the threads on the side with no screws so that I could fix the disc to the hub properly. Whether a previous owner used odd pads, or new and old mixed, I've no idea - but something caused this and I don't suspect stiffness in the carrier, because it didn't seem too bad.