If it's flat paint, that's a huge part of your problem. We have flat walls but glossier white trim in our rental and the trim is easy to wipe down but trying to get anything off the flat walls is much tougher.
I'm not sure whether you have control over the paint used at all but Sherwin-Williams has a line of paint called
Duration Home which is designed to be wipeable no matter what sheen it is. We've used it quite a few times and works really well. It's not cheap but they offer a lot of sales throughout the year if you needed to buy it yourself.