have seen this a few times now.

checked-in for my LCY flight to EDI yesterday (T-18 or so) and it looked like the whole front completely full with only a few seats at the back.

Flight ended up being 50% full towards the front (annoyingly - though no big deal on such a short hop - I had a neighbour who had the aisle and didn't move to an empty row). Had the same last week where I was expecting other pax all around me but was very empty.

Given this was case for so many seats, can't just be last minute flight changes. What's the reason for this? I probably would have sat myself somewhere else and just a bit confused that OLCI and MMB suggests all seats are taken when they end up being free.

Thanks.