Now here is another layman's take on it...if the original artist or owner does not take action to stop illegal use of their copyright material, they can actually lose their rights to it. At least that's what I've been given to understand when asking why it's so hard these days to find some of the original company logo decals for particular types of scale models. The mfg. must get permission from the company who owns the rights to whatever it is. Ford, Chevrolet, etc.
That applies very heavily to Trademarks and company logos are generally Trademarks which is a different protection under Copyright. And yes they must be vigorously defended. Famous case is Refrigerator - lost it Trademark protection. That's why Xerox keeps publishing ads telling people not to say I'm going to xerox something but rather say make a Xerox copy or photocopy something.
I'm not sure if mere Copyright is that vigorous but I'm way out of my league on that nuance.