In fairness, for most people there would be a difference between spontaneously shoplifting six 25p bars of fudge when you're starving, and the conscious, premeditated theft of £64 k from your employer when you aren't.
I agree that you can see a lot of her self-justifying mental processes at work in how she narrates that shoplifting episode, though.
For the previous several pages, she's been remarking pointedly on how former fishing villages now consist entirely of second homes, on the 'trinkets and pasties' of Tintagel and the building work going on in Polzeath, and how she seriously thinks about trying to snare a rabbit, as her father has taught her. The snack hut where she steals the fudge is full of people buying frivolous buckets and sweets for their children, and the money she thinks about repaying after she steals the fudge is needed for the ferry to Padstow, which is a sort of overcrowded Rick Stein-themed Disneyland where tourists tut at their packs and the icecream vendor refuses to refill their water bottles.
The whole episode says 'No one is more in need than us, or more desperate than us, therefore what I do is justified, and those who would condemn us are the kind of nasties who let their dog urinate on our tent or tell us we're disgusting for wild camping.'
Which I suspect is very much how her mental processes work in general.