I found the "commands disguised as a question" thread very interesting, because I'm usually on the other side.
I might say to my husband, "Do you want to empty the dishwasher while I make the lunches?" I'm not asking if he has a burning desire to empty the dishwasher, because I'm not crazy. There's a larger context to the discussion, which is that there are a bunch of things that need to be done, which we're both responsible for, but we're both equals here and I'm sort of trying to work out how we're going to do them, in a way that feels kind and acceptable to us both.
"I'll do it later after I finish this thing" or "I'd rather make the lunches" are perfectly acceptable responses, but if he just said "No!" and stared at me, I'd definitely feel upset and wonder why he's picking a fight.
"Why don't they just say what they mean?" ignores the fact that issuing blatant commands can feel rude, abrupt, and disrespectful of other people. I'm not going to order my husband to empty the dishwasher, because I'm not his boss or his mother, and that's not the kind of relationship that I want to have with him.
Issuing orders also only leads to "yes" or "no", while something less direct allows more room for back-and-forth negotiation that leaves both people feeling understood and respected. "Do you want to empty the dishwasher?" points out that it has to be done, and one of us has to do it, but it treats him like he has some say in the matter and can be part of making the decision. It adds a layer of respect for the other person and a general feeling of voluntary participation, and this can make social interactions run more smoothly and feel more pleasant for all involved.
To me, ignoring the larger context is like saying "Why would he say 'How are you?' if he didn't want to hear about my hernia operation?" There's more to communication than just literal translation of the words. Most people do understand what's being said, and purposely pretending not to feels mean to me. Especially when it's being done to an older woman who was trained never to say explicitly what she wants, who probably thinks she's being kind and polite.
I get how annoying it can be when taken to extremes, and I understand that there's been something of a cultural shift on this between generations. But there are probably better ways to address the issue than just pretending not to understand.