The mishna in Horayot 1:2 discusses a case where a court made a ruling that something is permitted and then later rescinded the ruling. Meanwhile, somebody did the thing they initially said is permitted -- is he liable? R' Eliezer says that one who is sitting at home is liable and one who has traveled overseas is not, and Ben Azzai explains that this is because the one who's sitting at home could have heard about the updated ruling while the traveler probably could not.
This explanation makes sense in general, but there are cases where somebody who's at home would nonetheless not hear about the updated ruling (for example, someone who is home sick), and we can imagine cases where somebody who's traveled far away could nonetheless hear about the ruling (for example, from someone else who later joins him in that location). I grant that the usual cases (in this time, not in our connected world) are as Ben Azzai explains, but it makes me wonder: why the indirection?
Instead of evaluating people's liability for transgressions based on assumptions rooted in geography, why did Chazal not make a more direct ruling: one who has heard about the update is liable, and one who has not is not? The practical effect seems to be that one who knowingly violated the court's (amended) ruling must bring an atonement offering, but that's something that the individual decides and does anyway, not something the community can compel, right? The person who knew but cites his overseas trip is still going to be held accountable before the divine court, isn't he? And is the one who didn't know, but was at home, really going to be held liable?