My late inlaws were really funny with food when visiting. Tiny portions for us, but smaller for me. Despite the children and I not liking Christmas cake or pudding, nothing provided instead, maybe just a bit of vanilla ice cream, while they tucked I to filling hot pudding, or cake. Had to bring non dairy milk, when child was on a medically advised exclusion diet, how difficult is it to pick up a couple of boxes when picking up bottles of cows milk at the supermarket, even when visiting in the train had to bring it. They did drink and provided beer etc but again nothing really for those who didn't drink alcohol. Wed arrive after a long journey having ket them know what time we aimed to arrive to find the meal has not been started, and the sleeping arrangements bit set up, wed have to do it, not fun with tired children. When children were old enough to visit on their own, on the train, I remember them arriving back home mid afternoon not having been fed before they set off, or given a packed lunch to eat in the train .
I could understand if we'd just arrived without notice, if you're not expecting people and you're planning to go shopping tomorrow so supplies are running low, then this would be easier to understand, but all the visits were planned well in advance.
If someone visited me unexpectedly and was needing to go shopping, I could rustle up a drink and maybe nuts, fruit or cheese if no biscuits (I try not to keep them in stock, am not supposed to have them regularly.
If I'm expecting someone I'd make sure to have something in, even stuff I couldn't eat, I'd pass it on to someone else if they didn't eat it