Depending on elevation, the type of parent storm, the ambient temperature, and other factors, the water content to snow can vary from 1:6 - very heavy chunky lake effect snow falling right at the freezing point, the kind you get wet just walking from the car to the door, to 1:12 , the kind typically seen in mountainous, more semi-arid locales. The fine white snowboarding/skiing snow. Generally the colder the air, the less moisture in the snow, same with height, unless it's precipitating out due to orographic uplift first.
anecdotally I think I've had to scoop about 30l of snow in a stuff sack, to get about 2-3l of melted water (of which I've probably added at least a cup or 2 of water to get started - to prevent the bottom of the pot being scorched by heat before the snow melts), so that sounds about right.
1. The volume of snow to be collected would have been significantly greater than the resulting water.
2. Heating snow at elevation requires more energy.
3. Perhaps getting snow into the steam generator wasn't so easy.