In the US the Supreme Court decided in 2018 (Carpenter v. United States) that people have a reasonable expectation of privacy even out in public.

This is not true at all. Carpenter v United States only decided that accessing CLSI data without a search warrant was unconstitutional. And it re-iterated that this only applies to CLSI data.

This decision is narrow. It does not express a view on matters
not before the Court; does not disturb the application of Smith and
Miller or call into question conventional surveillance techniques and
tools, such as security cameras; does not address other business records that might incidentally reveal location information; and does not
consider other collection techniques involving foreign affairs or national security. Pp. 17–18.