I use my wheelbarrow to do work around my mountain property all the time. We have a 4-wheel utility cart that sees a lot of service too. Their utility lies in doing work over short distances.
So then we can conclude that for the type of work they did, in the area they did, they did not find it practical to use anything wheeled to help out. They knew about wheels, as already mentioned, so they obviously would have utilized wheels if that would have been effective. And they didn't, so it wasn't.