The key language (which is why I posted it) are the words that one can only
travel in these electric wagons on shabbat if they are driven by non-Jews "
ub'rechovot sherov toshevim hem lo Yehudim". That does not say that the
majority of the streets they pass through must have a majority non-Jews., or
some of the streets they pass through must have majority non-Jews, but that
for taking these these wagons (or buses) to be acceptable, they must solely
be driven in streets where the majority of the inhabitants are not Jews.
Otherwise it looks like they are being driven down those streets for the
Jews.
Nor does he say "*only* in streets...". I think the expression "in streets" refers to the whole line, not to each individual stretch of road along it. Because I don't see how it matters why the bus is going along that stretch of road when it could have been rerouted to go along a parallel road; what matters is why the bus is running from the beginning of the line to the end of the line at all, and that is for all the people who have occasion to travel along any part of it.
Perhaps it is clearer in his summary (the original quote was from the body
of the teshuva, where he gave his reasons):, - . -
It is forbidden to travel in these wagons even if they belong to non-Jews,
and are driven by non-Jews, if they go and stop in a place in which there is
a Jewish settlement, then for sure it is that the non-Jew is intending in
his journey that Jews should travel. But in a place where all the dwellers
are non-Jews, it is permitted.
Wait a minute. He doesn't say anything about where it stops. Just where it goes. There's nothing about stopping in that passage, or in anything you've quoted. And by I think he means a Jewish population. That's why it's certain that the bus must be running for that population. Also when he says "all the residents are not Jewish" I don't think he can possibly mean that literally; he means the majority.
If the line exists to serve Jews, then it is not a non-Jewish line.
Sure it is. If it's owned and run by non-Jews, as is the case everywhere in chu"l (except the frum community buses, which obviously don't run on Shabbos so they're not an issue), then it's a non-Jewish line, even if it exists primarily to serve Jews.
Rav Uzziel was chief rabbi in, inter alia, Salonika, he spent a lot
of time in chutz l'aretz,
Other than his two years in Salonika (which he took while on temporary leave from his rabbanut in Yaffo) and a brief period of forcible exile in Damascus, when did he live in chu"l?
and the suggestion that he was discussing Palestinian or Jordanian
transport in Arab areas when he was permitting travel on Shabbas (for
the mitzvah of going to shul and similar only) seems highly
unlikely. Most people wouldn't use that transport for pikuach nefesh
reasons, not ask shialas about whether they can use it on Shabbas to
get to shul.
My understanding is that this was not the case for a long time. There was relative safety, at least as much as there is on public transport in some chu"l cities.