As Auntie said, not many folks have one sitting around their home, and you'll likely to have to survive going through a horde to get to somewhere that had one, and where might that be. Imagine if you barely survived getting past the Zombies, and getting into someplace you thought
would have one, and then find out there isn't one there, so, you have to survive through the horde again to continue your quest. And then of course, there is the lack of mobility she mentioned.
Sure it would be a decent and maybe even a great idea, if you happen to have one, or have access to one, but, what are the odds?