Much of Western Zen practice is modeled on that of Japan -- as would be expected given its origin in the West among immigrants from Japan in the 19th century. Too often, though, I think Zen practice in the West is completely divorced from its Japanese cultural, political and economic context, though not necessarily divorced from its history.
The history points to lines of transmission of the dharma from the Buddha through various teachers in India, then China, thence to Japan where three main schools of Zen developed from Chinese Cha'an Buddhism, and so here we are today. Most Western Zen practice amalgamates these Japanese schools without getting into the weeds of how they came to be and what their differences are and the many and sometime bloody struggles between them.
When the roshi tells you about the peaceful intent of Zen Buddhism, question it.
I've mentioned that Zen is in some respects a warrior cult, and Zen monasteries are partly modeled on samurai training. Zen's origins in China provide the foundation, but the development of Zen in Japan was closely tied to the samurai and feudal Japanese culture. Zen flourished (and was sometimes repressed) under the Shoguns, particularly so, it would seem, under the Tokugawa Shogunate, the ruling power in Japan from the 1600s until the Meiji Restoration of Imperial rule in 1868.
Zen declined from that point as did all Buddhism in Japan. The Imperial Shinto cult took its place. After the War in the Pacific, as it is called, the Imperial cult declined, but Buddhism, for the most part, did not revive much. Irreligion and secularism became the model to follow under American occupation after the war, but gradually Buddhist and Shinto practices reasserted themselves.
Zen, it must be understood, was never universal or even the dominant school of Buddhism in Japan. It isn't now. It is a special practice meant for a certain class or quality of individual. In old Japan, that was generally the samurai and some elements of the Shogun, Daimyo and Imperial households. In other words, very much upper class. Of course the lower orders could practice zazen, anybody can. But the hierarchy of Zen teaching and transmission, and admission to the monasteries was not open any but the "right sort", and the right sort usually meant high born and wealthy.
Monastic Buddhism can be criticized for being very class conscious. It's hard not to be, I think, given the Buddha's own princely origins. His example may apply to all classes, but he couldn't help being the aristocrat he was. His monastic life was outwardly poor and simple, but it was an aristocrat's expression of poverty and simplicity, not at all something grown from the bottom of society.
And so it has been with most monastics in the West as well as Asia. I don't criticize Zen or Buddhism for its classism, but I do acknowledge it, just as I would with Catholicism or any other religion.
St. Francis, my adopted patron saint, was also the son of an Italian merchant-aristocrat and a high-born French woman.
To see these high-born men and women putting on robes and going out begging is rather stunning when you think about it. But that's the way of monastics. Has been for many long centuries.
That aside, I think it's critical to recognize -- and honor -- Zen's Japanese origins without necessarily "turning Japanese." We in the West don't have more than a very superficial and probably erroneous understanding of Japanese society and culture and how Zen is integrated within it. We may be able to see and touch its outer shape and form, but Zen teaches us that's an illusion. We see nothing, really, because there is nothing really there.
Why would we put on robes or go on pilgrimage or chant the sutras? There's nothing to find, is there? No merit is gained.
There's nothing to learn, nothing to gain, nothing to have, nothing to be. Zen teaches knowing nothing.
There's a cow-kitten at my feet playing with a catnip fish taco.
That is Zen.
Other household cats will practice zazen randomly. We could ask "Does a cat have Buddha nature?" But why? Do the cranes flying overhead know and practice the dharma?