All true, however, how do you surmise that the performance by Servisair (soon to be Menzies) and Aviance before them are somehow inferior to BA ?
Corporate memory. When I flew GLA-LHR with BA in the 90s, BA handled their own flights at Glasgow with staff who had been there for years, had some discretion, were allowed to exercise judgement in certains matters and were somewhat older than today.
Nowadays we get minimum wage from Servisair and Menzies who joined the race to the bottom of ts and cs for aviation ground staff. I wouldn't get out of bed for what they pay their people, indeed some pay about the same as Tesco. Hence turnover is
brutally high and there is little customer care. Meet turnaround targets and bid a lower price in the next tender is all that matters. BA were far from perfect but at least the staff appeared to care about their company, not quite something to be found at Servisair and Menzies.
I wonder whether this is UK specific as handlers in Europe seem to be a little more, switched on shall we say?