Colin, the price of the app/content is irrelevant. Terms of use, terms of service, whatever they want to call them -- those are legal agreements.
One of the reasons that Apple and Google are paying up big fines is because they made contracts with people who have no legal standing to make contracts.
Have you ever clicked on an "I agree" button? You know, one of those buttons that if you don't agree, you don't get whatever you would get by agreeing. What you are agreeing to is the terms of use, all that legal mumbo jumbo that says you can't sue the person/company providing the app or whatever to you, the limits of their liability is to refund your money, etc. Many times, you're also agreeing to let them know your exact location, give them access to information on your phone, etc.
The point is this: you can't make that contract with any provider until you're 18 (or 21 in some countries). Most teens (and too many adults) will ignore the terms of use in their haste to d/l that awesome app all their friends have. For instance, d/l the Instagram app and they ask if they can use your location... sure! why not? Teens don't often stop to consider the risks in publicly posting their GPS coordinates... Hopefully, parents are a bit more discerning.
Meanwhile, exhale. You'll be 18 soon enough and then have a lot of years to wish you were a kid again.