Some phone service providers do not operate internationally. Those that do provide a "roaming" service. While their users are roaming in foreign lands.

Cell phone plan. My moms phone charges her extra to use data outside the continental us. I have international roaming, so i dont get charged more in other countries

Same for me. I just assumed the developers were getting lazy about creating new content as we progress through the course.

Not necessarily. Some plans are more limited, even domestically, by network coverage. Though in the US, I think this is less common that it used to be.