The 'industrial' in the title is doing real work. Small amounts of trans fats occur naturally in dairy and in meat from cattle and sheep. The ones public health people go after are the partially hydrogenated oils that used to be in everything from margarine to packaged biscuits.

I didn't know there were natural ones. Is there evidence they're less harmful, or are they just harder to regulate away?

I'd want a nutritionist to answer that properly rather than me. My understanding is that the evidence is less clear-cut, and the amounts in a normal diet are small. The industrial ones were in much larger amounts, in much more food.