The kratom industry is filled with shady people and greedy wannabe entrepreneurs and outright thieves. Tons of "reputable" sites are nothing more than slick web-design to give the illusion that they care or give a shit. They don't. They just want your money. And if the kratom plants drew water from a super polluted and unregulated river, tough shit for you, the consumer. Oh sure, they'll post their "results" from some bullshit fake test. Remember that there is a lot of pollution in the regions kratom comes from. It's not all pristine jungles and no industry.
Personally, i like the hungry hungry "fill in the blank here" site. That site showed me that the whole "reds are slow", "whites and greens are fast" is complete bullshit. There are slow whites and there are fast reds. And while it tends to skew that reds and yellows are slower, it's not always the case. This dovetails to what I believe you're talking about. "Red bali" from one place may be completely different from "red bali" on another site. Again, most of them don't care. They give the holistic bullshit answers and act like they care. They don't. They want your money. And if posing as do-gooding plant-loving hippies is what sucks the loot out of your wallet, that's the lengths they'll go to. And if the plants are drinking water from a river that has a shirt factory up river, again, tough shit for you. Gas station attendant don't care, if you catch my drift.
I don't mean to be a promoter of the aforementioned happy "animal that kills the most people in africa each year" (hint #2), there are some other good, well-meaning vendors, who do care. But be skeptical. Be critical. The soil, the weather, the alkalinity/acidity, the fertilizers, all these things can have an effect.