I’m sure someone has the Vimes Principle of Economic Unfairness on hand.

I’m also sure that there’s a slope for every product showing the durability and the price required to achieve it. Then there’s the reputation cost of making a cheap version and expensive version of something. If you make something flimsy for $5, it’s unlikely that someone would buy the indestructible version for $100, even if the cheap version was intended to function as an example of what the expensive product can do. Given an ethical vacuum, I think there’s great incentive to do the mediumest you can, even if you have a monopoly.

The ethics are going to be different for every product and every person. If you care about whales, indestructible fishing nets will seem evil. If you make something biodegradable, it will necessarily be flimsy, and that limits its long term usefulness. When the owner of an indestructible item dies, what’s to be done with it, and by whom? I think society would need to be radically different to even begin to answer this question.