Great if you live on a route popular enough that they do that. You are screwed otherwise. Even if you do live on a popular route, it also doesn't solve the problem if you want to go somewhere unpopular.
>I do not find it particularly urgent to make long-distance trips - presumably for leisure - within ten minutes of making the decision.
Good for you, but not that relevant for people that do. Waking up Saturday morning and deciding to drive out to a destination like this, spend the night, and then drive back the next day is not considered unreasonable.
>The bigger question is - why is it strictly necessarily to have to use it for ten minutes - just to get milk?
Because I need milk for a recipe I just found online and I don't want to wait 15 minutes for the next train, ride for 10 minutes, shop for 5 minutes, wait 15 minutes for the return train, and then ride for 10 minutes. And those times even generously assume I live right on a stop and there is a store right on a stop.