So, the people who just came couldn't find any medicine in the area they were in because it was already thoroughly cleaned by the survivors and army of the north base.
It was only a day away from the north base, so the north base would likely monitor the situation.
And a lot of people would also travel through it when they wanted to enter or go out of the north base, so even if it's still a day away from the north base, it was safer.
So, people who had some courage could certainly go and get some necessities from the area they were in because the danger level was very low.
The people below likely don't have anyone with them that could at least harden the deeper parts of the snow so that they won't have to worry about being obstructed by the things under them.
That's why their car turned over, and they couldn't continue using the car because a lot of obstacles were still around, like the zombies covered by the snow, objects thrown around, cars, and a lot of other things.
