The explanation being offered for it 'not being a DIY job' was that a poor/loose connection could lead to fire. That's obviously true, but probably not much more so with meter tails than with, say, a shower isolator (and overheating of the former would probably be detected much earlier, probably before a fire started, in many/most houses).
About the only possible 'mistake' I can think of (other than not tightening the screws enough) is incorrect polarity, which is pretty basic. It would be nice to think that anyone reconnecting meter tails would undertake polarity checks afterwards 'just to be sure', but I have to say that I've never noticed a 'meter changer' do that! (maybe I haven't been paying enough attention)
Kind Regards, John
