The answer for this question is the same as for all the other questions of this type: because it is not "asher kidshanu" – there is nothing Jew-specific about it. Jews and non-Jews do it alike, and therefore it is not a distinctively Jewish mitzvah.
Also no beracha for Tzedakah and Kibud Av v'Em for the same exact reasons. This is written in the link that you yourself shared in the question (a few clicks and footnotes apart from there):
The Aruch HaShulchan YD 240:2 explains that the reason there is no
bracha for Tzadaka is because both Jews and non-Jews do this deed.
Since the primary difference between a Jew and non-Jew who take such
actions is the intent, that the Jew does it in order to fulfill a
mitzvah and the non-Jew does it because its moral, for such an action
one may not say "Asher Kideshanu" - we were commanded in this specific
UPDATE: Here in an earlier, similar question the same answer is brought in the name of Rabbi Elazar of Worms (Rokeach):
Rabbi Elazar of Worms (c. 1176-1238), writes in his Sefer HaRokeach
(ch. 366) that the Sages did not ordain a blessing before any mitzvah
like tzedakah, which is based on logic and common sense and is
therefore performed by non-Jews as well. The reason for this rule is
because the entire purpose of our doing mitzvos is to sanctify
ourselves and to help us lead more elevated and spiritual lives than
those around us - as we say in the standard form of blessing before
performing a mitzvah: Who has sanctified us with His commandments.
However, when performing a mitzvah that is also performed by non-Jews,
as in the case of tzedakah, our sanctification as Jews is not readily
evident and thus no blessing is recited.
Why don't we say a blessing before giving charity?