Begging and performance art

Farrar reports on a journalist's experience with begging; the journo apparently earned reasonably well. I'm not sure we can extrapolate from his experience to that of others. But here's the more interesting bit from the cited journalist:

The IRD said my begged money is considered a gift and does not attract tax. That is unlike street buskers, who are supposed to declare their earnings.

How does IRD draw the line between street performers and beggers? Surely some beggars could be considered performance artists, and some performance artists are of sufficiently poor caliber that donations would be more akin to gifts (a link would be too cruel). Drawing lines is never easy.