Back to Squirrel Hill, I saw some media I hadn't noticed when leaving home. The stickers on the car are certainly media. They are not controlled by any companies or shops, not controlled by any kind of capital. It's just purely out of personal intention of the car owner. I find it more like posts on Facebook: personal and suggesting "who I am".
In the end, I just want to say something more general. Those media which are at unnoticeable places are usually public service advertisements. Maybe it is suggesting that most media are still in the hands of those rich and powerful people. And other kinds of media, which are unnoticeable simply because of being merged into surroundings, still have effects on us, even though we might not realize. Such as the Billboard I mentioned before, it perfectly becomes part of the environment and we just enjoy the sight of it. Furthermore, like the sale boards in shops, they pass sale information to us. Because media are so common in our daily life, we are affected by them anytime and anywhere in so many ways without realizing them. People might be easily manipulated by media around them if they do not have abilities of critically judging media. They might be exerted with different emotions or subconscious intentions by others. If we carefully think about those media-related issues, we might find those issues can be legal, moral or even more serious.