system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does using data on phones cost so much money?
gpt
One reason is because they can - they control your ability to connect to the internet from almost wherever you want, so they can charge more for it than you would pay for home internet.

Another reason is that it costs them a fair bit of money to build and maintain that network, so the cost gets passed on to you, the customer.