love to both pay for shipping and carrying home 95% water
Well, they put it in the refrigerated section just so people see it as legitimate milk. So that's your answer
yes but I'm lazy and want them crushed and mixed with oil and vitamins
The texture would be fucky unless you use a blender. If you're using a blender, might as well just make your own milk.
cow milk is one thing since you need to actually dry it first, but plant milk is literally just a concentrate that they add water to even when they don't need to
I don't think that's necessarily true. Like, yes, at the basic level, plant milk is just a mixture of plant concentrate and water, but depending on the process required to get the desired flavor and consistency, it might be more complicated than just mixing two things together. I think your premise is valid, I'm just saying that I wouldn't be surprised if plant milk from concentrate is harder to get right than having it mass manufactured in a controlled setting. With how fickle consumers are, you can't take the risk of putting out a product that isn't exactly what people are expecting. They just won't buy it. Woo capitalism, love consumer choice.
My oat milk homemade has always turned out pretty slimy, have never been able to match Oatly
Tried it, tried a lot of different methods. Cold water is recommended too, but still they come out slimy and not nearly as sweet at Oatly, which uses a specific enzyme method to turn some of the oats into sugars without adding any additional sugar.
I work in flavors/food production, and while I don't have experience with plant milks, the likely answer is that homogenization of emulsions is unfortunately not always as simple as adding water and shaking it up. There is probably special equipment and mixers involved.