AFAIK, while the Japanese OEMs want their own fluid there's a defined standard - JASO M315-1A and it's called in the Japanese aftermarket as "superior type" ATF. That standard builds off the Dexron standards but it also adds onto it. There doesn't seem to be formal process to license that spec, all the additive manufacturers and blenders seem to self-certify to it.
Nissan and Honda are OK with their latest service fluids(Nissan-Matic S and DW-1) for their older units but Toyota doesn't want WS going into T-IV units. There was a TSB out saying using WS in a T-IV unit will result in shift shock and possible fluid spray/leakage and T-IV in a WS unit will cause delayed engagement at cold temps and increased ATF temps/decreased MPG. However, except for softer shifts, I've used MaxLife in two T-IV boxes without seeing leaks or ATF spraying out of the breather fitting. Honda's new 10-speed now calls for a different fluid(Honda ATF Type 2.0, their relabel of ZF Lifeguard 9 is ATF Type 3.1).
With that said, I feel OK with MaxLife or any JASO M315-1A fluid in most Japanese and Korean transmissions. Shift feel is subjective. I'll stick to T-IV on older Toyota units. If I ever touch a GM/Ford/Mopar transmission, I will use licensed fluid and Euro stuff will get the right fluid.