Free Advertising

Why do we as a society accept the fact that certain companies try (and succeed) to advertise for free?

Next time you're out driving, count how many cars have dealer license plate frames or better yet, the decals of the dealership right on the trunk. Do you get commission whenever someone buys a car because they saw the dealerships name on your car? "Wow, check out that hot redhead in the Denali. I'm going to Bill Jones GMC right now to buy me one of them"

And just as bad, what about the clothing manufacturers? You buy a Brooks Brothers shirt and it's got the little sheep on it. That's totally cool. But I'm talking about the shirts that says "NIKE" really big across the back

Shouldn't Nike be paying us to wear these items (maybe not this guy)? Or at least giving it to us for free?