It almost sounds like you're suggesting that if we use any plastics for convenience then we have no right to ask corporations to not wreck the environment wholesale.
I use plastics, but I dispose of them in the trash or recycling, and I sure hope they don't end up in the ocean. If they do, then I'd be happy to work on a government solution to not have all our trash end up in our food. So comparing using packing to creating pieces of plastic in shampoos that nobody asked for that go into waste water is not reasonable.
Also packing materials is a terrible choice because I can't choose my packaging materials. I'd be fine if all my things were packed with paper, it just saves amazon 20 cents to use styrofoam peanuts. I'd gladly pay 20 cents more for paper-only-packaging.
The other point is, you're making the whole thing unreasonably black-and-white. If you think that consumers are the problem, why not come up with some kind of research that explains why most of this plastic in this fish comes from things uniquely under a consumer's control.