@louloulemons yes I agree, it's "dropped" stuff rather than "placed" stuff.
One island from this thread which I visited recently had a great way to avoid this while still offering DIYs - log tables and benches all covered with DIYs. So long as you drop them on something other than the ground, you're OK.
I have some customised stalls on my beach for my giveaways (but the log tables and benches were a better approach for a higher volume of stuff).