My. Your points are exactly the kinds of reasons that folks like me are trying to get intentional communities to regulatory parity with nuclear family-oriented lifestyles.
You're right, living the way that you do and disposing of your "waste" the way that you do, every little change is tiny gain trying to justify significant cost. But out here in Oregon more and more people are living illegally, getting by with less access to mortgages, violating fire codes, and so on to live five to twenty people to a household. But since regulations are designed to obstruct adding more bathrooms, they tend to have to share them even though they would gladly pay the cost of building in more. Since water regulations make it a crime to put their greywater on their gardens, they sneak it out a little at a time and never put in efficient dedicated greywater plumbing. Since putting a greenhouse on the lot would also be a tell of those illegal people, not to mention unfundable with a second mortgage shared by all those people, instead they build cheesy little ones out of scrap and grow a third of the food they could, using twice the space and adding almost no living space to the house. And on and on.
Why do I bring all this up? Because in a two or three person household, you're right, this kind of thing is all pain almost no gain. But the larger the household, the more practical it gets to either sort into more categories or perhaps even build a little homebrew-style setup and do the diesel separation right there. Yet again we see that the real barriers to living sustainably trace back to our corporate-backed, fifties originated, "nuclear family" lifestyles.