Share App Store, iTunes Store, and Apple Books purchases with Family Sharing - http://support.apple.com/HT201085 - "To share purchased content, all family members must use the same iTunes Store country or region."
The content available depends upon the country to which the Apple ID is set, not physical presence. However, Apple does say, "Certain Services and Content available to you in your Home Country may not be available to you when traveling outside of your Home Country." - https://www.apple.com/legal/internet-services/itunes/us/terms.html
From that I gather that if a person is not in their Home Country, and Apple detected that, it could prevent service from being provided if it wished to. Also note that according to the terms of service: "Our Services are available for your use in your country of residence (“Home Country”)" and, "By creating an account for use of the Services in a particular country or territory you are specifying it as your Home Country." A person setting their country to one where they are not resident would therefore be violating Apple's terms of use.