You make it sound as though this is such an obvious distinction that Apple could never get a trademark for "app store". But apparently this argument is not so strong in trademark law as Apple actually has the trademark already. If that were not the case how could they sue another entity for trademark infringement?
I think all of you who believe you have trademark law all figured out should keep this in mind. Apple has a trademark for app store. Previously another company had a trademark for "appstore" which is very similar.
You can write about the topic as though you have it all figured out but clearly your interpretation is not definitive as Apple was awarded the trademark.
Now perhaps eventually apple will lose it or have to modify it but the fact that they got the trademark and a legal battle would need to be waged for them to lose proves that your opinion of trademark law in this case is oversimplified.
It was.
Can you please show me the trademark that was granted to Apple for App Store by the USPTO? You won't be able to find it because their trademark has not been approved. An opposition to their application was filed, if you didn't catch that from the text.
Trademark is having property rights in a trade name. Apple, or any other company, can file to protect a trademark they have been using and the USPTO decides if it is too generic to be an actual trademark. I suggest you learn about the process of how trademarks.
"How does a mark qualify for federal registration?
To register a trademark with the PTO, the mark's owner first must put it into use " in commerce that Congress may regulate." This means the mark must be used on a product or service that crosses state, national or territorial lines or that affects commerce crossing such lines--for example, a catalog business or a restaurant or motel that caters to interstate or international customers. Even if the owner files an intent-to-use (ITU) trademark application (ITU applications are discussed in the previous set of questions), the mark will not actually be registered until it is used in commerce."
Source:
http://www.inc.com/articles/1999/10/14646.html
Also, take a look at the Lanham Act, which is pretty important when it comes to trademark law
http://en.wikipedia.org/wiki/Lanham_Act <-- particularly Subchapters I and II.
Just because you use a mark does not mean you have been granted the trademark rights in it.
So, as you can see Apple does not have the trademark to App Store. Therefore, your argument fails on that premise alone.