I don't know. I think "by" implies creation/ownership of the company in that case, but the important part is what it provides, not who owns it. Just like the GP, does "Water by Black (Whatever)" really have a draw? Some people may want to support people they identify with, but I think most just want a good product, so the trick is making sure that product is easily identified for those that are interested in it.
Maybe trying to call to associations with BET is enough, and something like Black Streaming Entertainment (BSE, to avoid possible problems with BES) would be enough? Although if it's free, to my eyes BlackStream seems like it would be ideal.
> My point is more that for somewhat implies exclusion, while by doesn’t.
I'm not disagreeing with that specific point. Just making a corollary that by doesn't necessarily identify what it is in all contexts, as it's more ambiguous depending on where it's used. For a restaurant, it's fairly obvious because we have prior assumptions about the service. It it was laundry, the assumption might just be it was advertising itself as a black owned business. For a streaming service? Probably more on the side of how a restaurant is seen, but why even court that confusion? Most restaurants would avoid it as well, and call themselves Soul Food or some other moniker that clearly communicates what it serves as opposed to who runs it.
"Restaurant by Black People" might communicate something about the restaurant enough to most people, but it's also just a poor choice of description all around. Netflix by Black People is similarly a poor description, IMO.
by, not for