The world could run on older hardware if software optimization was a priority

Well, yes. It's an economic problem (which is to say, it's a resource allocation problem). Do you have someone spend extra time optimising your software or do you have them produce more functionality. If the latter generates more cash then that's what you'll get them to do. If the former becomes important to your cashflow then you'll get them to do that.

I think you’re right in that it’s an economics problem, but you’re wrong about which one.

For me this is a clear case of negative externalities inflicted by software companies against the population at large.

Most software companies don’t care about optimization because they’re not paying the real costs on that energy, lost time or additional e-waste.