system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do Verizon and AT&T both claim to have the nation's largest network?
gpt
There are different ways you can measure largest...number of customers, number of towers, square miles of coverage.

On top of that, "network" is also vague...is it phone service, internet service, 3G, 4G?

So it is is pretty easy to pick and choose a definition that could make either one the largest.  In ads, you'll often see an asterisk and some fine print describing the exact criteria.