Contrary to all the Western BS about "samurai caste" etc. (it's always some dim-witted "academically proven" stereotype with you folk), the Samurai completely lost their power during the Tokugawa period due to inflation.
Meiji broke this completely, and gave power to an oligarchy consisting of rich merchants/farmers (and some their samurai co-conspirators who helped with the restoring Meiji to power.). In fact, this transition was helped by the British, which might explain why Meiji was so anti-Asia to begin with - there was an incomplete purge of Buddhism and conscious playdown of Chinese culture.
B. Sure, the samurai lost their political power by the Meji period. That doesn't mean their social and cultural influence disappeared overnight, especially since the country spent decades more or less under the thumb of the Imperial Japanese Army....who saw themselves as carrying on the samurai legacy, well within living memory for some Japanese. In the 30's and 40's it permeated the school system, so generations of Japanese grew up with that same military discipline, inherited from the IJA, who inherited it from the samurai.
They sure as hell didn't get rigid selflessness and tolerance for suffering from rich merchants. Plus they still form up for morning PT sessions at corporate jobs! They just have the intensity dialed down to.....1/10. Do you ever see this in any culture that hasn't had a strong military tradition?
Couldn't find a decent video of Marines doing company-level PT for comparison, but here's Army Basic Training at "Relaxin' Jackson" (everyone pokes fun at graduates of this base for producing the softest Soldiers): https://youtu.be/cIVWU8hyuI0
There may also be other factors, but I think this is one.
Also there is a lot of weight placed on seniority, so younger people have pressure to work harder to make up for what they lack in experience. While a little less common now, it used to be understood that you shouldn't leave work before your boss.
I suspect sometimes it's just a matter of a few large employers setting people's idea of what "normal" is.