.com is for Comcast right? Comical tech assumtions by my mother #1

In my everyday life I get asked certain things that make me want to rage, but I have to stop and collect my thoughts. Things we take for granted in the tech world are foreign to others. My mother is extremely smart, and has taken to the internet well. But at times her assumptions about how certain things work amuse me. We recently swapped from Uverse to Comcast, so she assumed the new place to check her email would be found at Comcast.com, whereas we all know your Comcast webmail is to be found at Comcast.net. She replied "but .net is for Yahoo & .com is for Comcast" She had assumed .com quite literally stood for the first three letters in Comcast. Her logic system failed her when I asked her why .net stood for Yahoo... nonetheless, I tried to explain that the .com domain is not part of Comcast, but rather the greater common wealth of the interwebz.