The thieving old lady HAS an allotment - bigger than mine, and quite well run, too!
I've had a quiet word with some of my neighbours, and it seems everyone knows about her. Three of them had words with her about it last year, but she just shrugged and moved off. They don't want to kick her off the allotment, since it seems to be the centre point of her life (her husband is around sometimes, too, but he seems less involved).
Basically, everyone is just waiting for her to die.
As for surplus, my plot measures 3 X 4 metres - I'm in the middle of Oslo city, so plots are too tiny for there to be any surplus. (She nicked another cabbage last week - her feet are tiny, and I could see the small print in the soil where she stood to pull the plant up.)
The amount she steals seems to be much larger than anyone could eat on their own, so there are speculations that she distributes to friends or neighbours.