More on the situations that don't have eruvin - for example, the rooftops that are one domain do not join with other areas that don't have an eruv. Though you can carry within the courtyard - things that were already in the courtyard. Plus - R. Yehudah HaNasi was learning Torah with R. Shimon, they'd carry oil and a towel with them, for their shabbat trip to the spring. Plus - in the time of "danger" - decrees against the Jewish people - ends up being the kind of time that can't be used for precedent. Also - R. Shimon's view seems to be that the entire great outdoors is one domain. Which seems to undermine or disagree with the premise of needing an eruv chatzerot. Which is flabbergasting. And not how we do "eruv" today.