Why did Japan have the Samurai and Bushido so pronounce through karate-do. Others had their own warriors, but why is it was/is different?

Karate is Okinawan, not Japanese and didn't make it to mainland Japan until 1922 through Gichin Funakoshi which is long after the Samurai class in Japan was abolished (1873).

Maybe it makes the Japanese feel it is more of their own if they insert their own tradition, a tradition that was important in Japanese history and would otherwise be lost altogether since it was abolished. Remember they do not like the Okinawan and treated them brutally when they invaded Okinawa. Admitting that something really cool that they accepted came from such inferior people might be a blow to their ego so you make it look like it is yours so you don't have to give anybody credit especially not someone you thought less of.

From what I read in Asian history books is that Bushido is the "way of the warrior." During Japans feudal era (under the feudal [cast] system the samurai were the "warrior" class, they had to born into. They were the only ones that could carry two swards. Their cast set them close to the top of the hierarchy under only the emperor, and/or shogun & lord, and priests. They wrote that there existence was only to die serving the emperor and lord. The way of the worrier was only budo (the art of killing) as so carried withing Japanese culture from the Heian & Sengoku to modern day. Karate-do is of Okinawan roots and manifested in Japan so the idea behind karate remains within the art. Only warriors elites such as Spartans, Alexander the Greats pretorian guard, and Mongolians compare, at all, with the Samurai in this way. Karateka closely hold their own spirit close to that of the samurai. I could be wrong, but I doubt it.

Tes