Totally disagree!!
Depends how you go about it. Last few days resulted in a good 1kg haul, which is currently being put to good use, dried and chopped etc. Our encounters with locals were quite pleasant to say the least. We drove very slowly, didn't leave any rubbish and definitely did not damage fence lines, etc. so they had no reason to 'hate' us. One family invited us in for a cup of tea and advised us to check further up the track near the pine trees, and another lady came home as we were crawling around her front yard- she only asked to have a look, quite impressed at the size of some of them she suggested a spot behind the general store of the next town.
We were straight up, 'we are here to pick mushrooms', and no-one seemed offended or otherwise upset- we left no rubbish, no loud music and we were as friendly and polite as was expected.
Thinking back over the last few years, aside from the unfriendly comment of 'you're looking for mushrooms, aren't you?!' or (this was funny on the weekend) "daddy, there's someone hiding in the bushes!", "Don't worry, they're just looking for mushrooms!" , I've never had a bad experience with locals being neither jealous nor high and mighty.
Funniest is the strange looks when you get on the train after a whole days' picking (damn quite a few years ago), covered in mud, clutching a mysterious cloth bag