So, yes, petroleum products fuel the trucks that move things, and maybe the machines that work on items, or are in some things - we're just using petroleum as an example, of course.
What I do is say...how biodegradable is the product that I'll end up with? Or, is a larger size or a concentrated product better? Or, can I get a version which is made closer to me, so that it doesn't have to be shipped as far? Then, I make my choices that way.
While there are some great companies out there which make small footprint products and containers/packaging, a lot of times there's no perfect product. That's when you just have to settle for, and support the guy who makes, the least-harm version.
Sometimes I have realized that I just don't need something, but we have to be realistic, too. And, in your case, you need the cat litter for their health and happiness, and your sanity. So, you make the best choice that you can, and it looks as if you have.
Love All Life, Thank You For Posting! :)