I'm not here to argue. I think you're conflating multiple things here. Vegetarianism is lower pollution yes, but it's still delivered via truck or ship, it's still usually plastic wrapped, etc. Pollution is systemically embedded in our entire society and economy, so blaming consumers is only blaming the smallest part of the problem.

If everyone in the world tomorrow stopped buying anything that was polluting... They'd probably starve to death. Our farms and logistics are simply not designed for this. It's all been "optimised" for the lowest cost to companies and consumers both. The only solution is to start at the top and work your way down.

Let's say you're a company that sells food. You care about the environment so you switch everything to green. Electric trucks and ships. No plastic packaging. Your operating costs triple, and you fall behind all your competitors. Most customers don't understand, don't care, or cannot afford your more expensive products, especially in this economy. You go out of business. The only way to make it work is to reshape everything so that pollution is no longer an integral part of everything. I don't know what that would look like though, I'm not that smart.

'because the alternative is going to cost them more'

This is one of those things that you have to let go of. While it makes sense, it is not a guiding factor for corporate decisions.