I find it hard to believe the original premise of this thread. We knew
there were some problems with OSX and FreeBSD but surely they can't be
completely broken? What happens if you run "ls" with your locale set
to something like fr_FR.UTF8 ? Does Apple not sell Macs in countries
other than the US?
There were a number of problems with using ICU including the large
dependency and the limitations of the iterator model but the main
issue was that it's fundamentally a choice between being consistent
with every other application on your system and being consistent with
other Postgres databases running on other OSes. Most people run
multiple applications on one OS, not many databases on many OSes on
their own with no other applications. If Postgres used ICU then its
output would be inconsistent with things like "sort" or "ls" or your
application programming language's comparison operators.