As you say, there are different kinds of rice that taste and feel differently, and you should use the right one for your recipe, but debating with a marketing person about their superlative is a futile exercise.
Surely this would be better served with a believable statement rather than blatantly subjective hyperbole.
The previous place I lived in had very hard water, and I found that running the water through both a coffee filter and then a Brita charcoal filter worked rather well to soften the water and improve the quality of the rice I was cooking.
That's aside from whatever harder-to-measure taste differences it might have, but it makes a big difference by itself.
I would be amazed if rice grown by Japanese immigrants like Koda or Tamkai couldn't reach the level and it really was the land that made the difference.
The only experiment I have found that attempts to measure this is by Kenji with pizza. In his test, the water did not matter.
https://www.seriouseats.com/does-nyc-water-make-a-difference...
Nishiki uses an offshoot of Calrose rice, which is okay but popular Japanese rice is often Koshihikari or Yumipurika: https://en.wikipedia.org/wiki/Nishiki_rice (do click the link for SICK web art on a random wikipedia page)
If you can find some https://umamimart.com/products/tamaki-haiga-rice is one of my favs.
Or as someone commented below the rice from The Rice Factory is solid if you are looking for a treat: https://trf-ny.com/collections/rice
I currently have 3 varieties from TRF in my cupboard :D
The premium brands of Japanese rice that I would buy were slightly better than the current Kokuho Rose brand I get now (this is the best I can find in semi-rural Canada). The biggest difference in quality were brown rice variants (e.g. genmai) that I have been unable to find anywhere else. But the short-grain white rice weren't so much better that I really miss them. The quality is maybe 5% better but the cost to have it imported here is more than double, so very much not worth it.
I'm sure it's excellent, but in the end, it's just rice. A blind taste test would be random noise. I sure can't remember there being a material different in the rice I ate in Japan vs good Japanese food in Cali.
Hell, even if you included jasmine or basmati, I'll bet most western people wouldn't even be able to tell those apart from Japanese short-grained rice.
Edit: western people
I'll beat your blind taste test everyday of the week just by rolling the rice around in my mouth
EDIT fwiw you can vaguely bucket 1.4 billion people into "eat basmati" 673M+1.4B people into "eat jasmine" and 150M+50M into "eat short grain" rice which is well over a third of the planet
I should have qualified that to randomly selected Americans/Europeans. And that they could understand each type of rice is different but wouldn't have a clue which is which.
As a cash strapped student I would buy Korean short grain as it was cheaper
It was a bit of hyperbole, but I think you'd be surprised how undifferentiated people's pallets can be if they aren't eating something constantly.
Tell that to my Japanese wife, LOL
We also buy the “Japanese” rice grown in California and she is never fully satisfied with it.
Though if we're talking specifically about heavy metals, iirc northeastern China has better (lower) heavy metal levels compared to a lot of other parts of China
There is an old Chinese saying that goes Live in Hangzhou, marry in Suzhou, dine in Guangzhou, and die in Luzhou.
But my wife is from way northeast, and I had to begrudgingly admit that I do like the rice from up there better.
meet Lexus LFA vs Corvette.
Totally not the point of this, but is Japanese rice really "the best-tasting"? Don't get me wrong, I enjoy California-produced Japanese-style short-grained varieties (I'm not sure whether I've bought actual Japanese-grown rice) -- in some applications. But sometimes you want a jasmine or a basmati or something else, and it seems like that's a matter of preference and what you're used to and what other food you're eating it with, more than "better" or "luxury".