I've got this friend, who similarly to the other topic going on currently, has problems with crud deeper than 1 inch (if that). I'm not sure he knows how to use his edges, and definitely cannot carve. In my opinion both of these would help ski and cut through the crud.
Things I've tried to help him are telling him to just tip his knees over (just realized "tip your ankles" may work better, haven't tried that yet), doing a railroad track drill, and power plow. None of these have worked so far, although at one point with the power plow he did cut a line in the snow, but was going straight instead of turning. But for the most part, he was still steering his skis, and leaving no track behind like in the video below.
There's a few things working against him. One is equipment. He skis with crappy rental gear. Although his boots do have aftermarket footbeds, they're probably still a poor fit. Also related to boots, I haven't witnessed this, but he said he stands in a plow position while not skiing, like when waiting in line for example. Second is an aging body, so mobility is limited. For example, in a sideslip position, his upper body could only be at 45° from the fall line instead of straight down at it.
This video is not a result of what I've tried to have him do, it's just his regular skiing. However he did get a lesson recently before recording this. Some of the things that were worked on were counter and skiing on the outside ski with upper body on the inside of the turn, both of which he has started to do. I know some of you will say to complete his turns (which was also mentioned in the lesson), but that's just boring on a small pitch like this.