I have a feeling the person in this story who got fined $500 was less than apologetic and made a fuss.
I suspect this was indeed a factor. As others have noted, there are prominent signs as you go through customs and immigration stating no fresh fruit (and a bunch of other things), but honest mistakes are seldom punished
unless you mouth off.
Years ago I worked with a fellow who married a British woman that he'd met on a trip to Rolls - and couldn't get her a visa to join him in the US. The guy was very abrasive and confrontational (very difficult to work with, I was actually afraid of him a few times) - given I was able to get my foreign born wife a visa in a few days, I'm sure he pissed off to the wrong person and they decided to make his life difficult. He did eventually get his wife a visa, but it took over a year...