I have had plenty of flights with LX where I was the only pax in C.
Mostly on late evening ZRH-AMS flights.
Perhaps the Dutch are a bit stingy ?

Anyway, the service was never very good, as all FAs were serving the Y cabin and completely ignored me in C. The call bell was usually also ignored ... but that seems to be LX standard operating procedure even in LX, as I found out recently.