It's up to the individual. Batman wouldn't give a rat's ass about a kid wearing a tee with a bat symbol on it. If he did, then he'd make up some dummy corporation responsible for copyrighting the symbol, and then have it sue the company making the tee, or mor likely coopt it. However, I don't think heroes would do much more than scratch their heads and go on kicking butt. Reality is, if the comic world were anything like ours, those people wouldn't worship the heroes, but be frightened of them. They are vigilantes with strange abilities, and somehow above the law. They would create an uproar and it would stigmatize the notion of wearing a superhero logo on a t-shirt. This trade-mark thing would imply that they are considered mainstream, and I believe they would be ostracized and debated over until some conclusion was met to regulate heroes, and ultimately not make them heroes at all. So, the issue of logos and trademarks would be moot.