I'm also courios about if, to make a review, you must have buyed an app or not...
If not, be prepared to have the store filled with this type of reviews.
There are only my opinions, and I like to hear other developers about this.
I'm a consumer, not a developer, but here are my 2 lira (or is it just Euros now):
You don't have to have purchased an app to review it, I agree this is a mistake. There are tons of reviews all over the app store saying "I would never pay X dollars for this app! Rip-off!" and I agree these aren't helpful. So I marked the review you mentioned as "not helpful." I'm not going to "report a concern," because that's really for something totally inappropriate, or hateful, etc. And I'm not going to post a review, since we both agree that reviews by people who haven't downloaded and tried an app aren't helpful, and, ummm... to be honest, I'm not going to pay $3.99 plus 7.5% sales tax for a shopping list app.
I know you didn't ask for any advice, but since you threw out your app and the comment to it on this forum, I'd suggest: 1) if your app is better than the other shopping apps in certain respects, then highlight those aspects in the description and screen shot; 2) people in the U.S. are very unforgiving of non-native English speakers, so ask a native English speaker to proof-read and revise your description (here, even saying "shops" instead of "stores" will put some people off -- we're very insulated language-wise; 3) speaking of language, also market any additional uses for the app -- I'm not sure if with all the language support, you can have multiple languages or not -- if you can, market it as also language practice -- learning names of foods and everyday items is useful to a language learner; 4) sorry, but consider (drastically) lowering the price. That's not to say your work isn't valuable, but you have to remember there are already over 300 paid apps competing with yours, and thousands to come soon (yes, you're competing with totally different ones -- if I have a budget of $30, then I'm going to be thinking about "Super Monkey Ball" when I consider your app, even if they're obviously totally different apps). I think you'll make up the difference, and then some with increased volume. I don't mean to tell you how to run your business, just giving you a U.S. consumer's point of view.