@RadZach nope, you are reading that correctly. Renters who are local to our area often like to use their own stuff anyways, and since they usually drive it back to their house after pickup to load everything, tossing in their own linens to use isn't that much more work.
I get it, some owners provision their rental more like a hotel or airbnb (with everything included for your stay), but optional linens is also common if you look at other examples. We do include pretty much everything else (outside camping gear, cookware, dishes, consumables, etc...) for all rentals. If we had a van with only one bed I would be more inclined to include bedding too, but we have 3 different sleeping areas in our class C, and washing a full set of linens between renters (towels, blankets, sheets, sleeping bags, pillowcases, washrags and such) is a ton of work.
