Of course they can, but sample sizes of each will have a big effect. If you flip two coins you have a decent chance of getting all heads. Far lower probability of that if you flip 10.

Apply the same analysis to a 5%, 1% or 0.001% chances of a poor BA F experience in any flight taken and it should help is all understand that there will be complaints - it's a matter of how many overall and the probability that one person will suffer multiple times consecutively (which will be especially noticeable if it happens in their first few flights).

My general view on this sort of thing is that given that failures all occur BA should be reducing them to an occurrence level where they can afford to offer compensation that will satisfy most reasonable customers, and actually offer that in a hassle free way. That may not be enough for some, but that's another stats game. If 95% are happy with the flight and 90% of initial grumbles are happy with the compensation that would see OK. If it's 80% and 10% that's poor.