I'm in no way saying it is the teachers' fault that they have had these non-teaching roles thrust upon them. Quite the opposite.
I really don't know just how government and the populace expect teachers to do their job in such conditions. No other profession would accept such role bleed, just as no other profession would be expected to deal with the level of abuse in the workplace that many teachers experience.
To me, it's indicative of a number of dynamics in society and goverment, most notably that the entire state education system rests on the goodwill of front line staff to a point where it pretty much takes the piss. It's the same in the NHS.