Or did you mean the kind of lpoliicies that count as "left wing" in the US, and liberal/moderate/centre-left everywhere else.

"Everywhere else"? I hate to break the news, but there are other places under the Sun besides the Anglosphere and Western Europe! In most of the world, both by population and surface area, and including some quite prosperous and civilized places, many UU positions would be seen as unimaginably extremist. (Try arguing their favored immigration policies to the Japanese, for example.)

You are however correct that in other Western/Anglospheric countries, the level of ideological uniformity in the political mainstream is far higher than in the U.S., and their mainstream is roughly similar to the UU doctrine on many issues, though not all. (Among their intellectual elites, on the other hand, Unitarian Universalism might as well be the established religion.)

In any case, I didn't say that the UUs had the most extreme left-wing positions on everything. On the contrary, what they espouse is roughly somewhere on the left fringe of the mainstream, and more radical leftist positions are certainly conceivable (and held by some small numbers of people). What is significant for the purposes of this discussion is the apparent ideological uniformity, not the content of their doctrine. My points would hold even if their positions were anywhere to the left or right of the present ones, as long as they were equally uniform.