Based on the OP, I was going to chalk this up to differing vacation philosophies. Some people like to lounge around after getting up, some people want to get ready and go as soon as they awaken.
But after reading the update in post #27, it sounds to me like Alice was being PA. She wanted to firm up the plans the day before (I agree with that!) but no one wanted to. She asked what the plans were that morning and was told "a couple of hours". So she decided to take that literally instead of reading the obvious cues.
And this brings me right back to my original read on this: differing styles. Most of the group is ok with playing it by ear and sort of going with the group. Alice wants a firm plan and will stick to it, by gum, regardless of changes which might occur on the fly.
The answer to all of this is, as PPs have noted, communication and planning. I've been on vacations with people who just want to lounge around and sleep in and who have a "whatever is fine" attitude. I'm totally a go-go-go, plan ahead, have back up ideas in case things don't pan out, kind of vacationer. The two don't mesh well, but no matter what, when vacationing with a group, it's always best to have things laid out in advance. It doesn't have to be a rigid plan, but it should be clear to everyone what the plan is (even if it's sleep in and lounge around).
And if there's any ambiguity, it should be cleared up as far in advance as possible. I don't think it was unreasonable for Alice to try to get firm plans agreed to the night before. And when she was told a couple of hours, well then, she figured a couple of hours. Like I said, I think she was being PA not to pick up on the signals, but I can see her making a statement in this case of, I asked for a definite plans to be made and I'd like that to happen.