The non-Abrahamic religions stick with thr peace and love parts in the US because they are not the dominant religion. Any religion ends up being cooped into being used to justify violence when it is on top even when the core tenets are supposed to be peaceful and accepting.

This also tends to be true of most human organizational structures, but religion adds a layer that make it easier for members to accept extreme behavior by the people in their group.

Buddhism was probably 10% the justification for nationalism that Shinto was in Japan, so that's a pretty bad example.

Also, using Buddhism to encourage nationalism ≠ Buddhisms fault

Moralists with authoritarian leanings are the problem.

Plenty of those around nowadays who, instead of a religions, latch on to some well meaning cause and then proceed to try and shove other people around under the cover of said cause, bringing along the more tribalist (hence unthinking and easilly manipulated with the right words) members of the cause, all the way to pretty much pogroms and purges (though, fortunatelly, not normally involving killing people).

Whilst the vehicle (religion, some ideologies, politics, any "cause" supposedly beyond questioning including nationalism), being something that most people follow in a mindless way is ideal for such subvertion and abuse as an easy source of supporting usefull idiots for people indulging their lust for power over others) the reall problem is, IMHO, a certain type of individual who will seek social situations they can abuse to be powerful (all the way down to the school social bully who uses connection rather than physicallity to have power over others), so it's really such people we should be weary of and alert for rather than their chosen vehicles.

Buddhism has a talent for conversion by syncretism. Tibetian Buddhism is Buddhism meeting Tibetian Shamanism, Chan/Zen is Buddhism meeting Taoism (which already was very close), both Therevada and Mayayana are rather more Hindu, and what we're seeing in the west is Humanist/Christian, depending on the practitioner. A good dividing line might be belief in reincarnation: Legit Atheists don't care, hell-conditioned folks find relief, whereas originally the whole thing was Hindu and Buddhism calls it dhukka (suffering, also mind that it's tied into the caste system) and promises a way to break out of it. So what was a jail in one context serves as a comfy blanket in another.

In that sense it's very much a mistake to see Buddhism as a uniform whole, or western adoption as appropriation or fetish, or really infer terribly much about one strain of Buddhism from the other.

Then, second note: All those eastern things should be compared, if you want to compare them properly, not to western religion or churches but to that and the whole philosophical heritage dating back to at least Socrates. And gods know in that context we don't need religion to fuck up, we're still recovering from Descartes and like to ignore inconvenient truths such that Newton was an Alchemist. Christians like to ignore that all the stuff that is actually valuable about Christianity, is more than memes furnished to propagate the system (and doing damage while doing so), is lifted from the Stoics. Racism once was "scientific". I could go on and on.