Lived in rural Australia with this as commonplace. Fwiw the neighbour did have someone take the whole box one day. He did run after it and get a numberplate since he was close to the box at the time.

That's one thing about these, it's not that no one would ever steal them as if there's some magic in these areas that leads to zero theft. After all anyone can drive out there. They exist because there's little choice but to accept some losses since you can't staff a store selling small amounts of produce.

For all the comments along the lines of "society has gone to shit, look how nice it once was" just remember that theft still happens and these honesty boxes were always done out of raw necessity.