Regardless of what answers there are to an alternative (there are many, with both flaws and benefits that could work better or could be worse in practice), the question “how would it work at scale” is probably impossible to answer thinking in the framework of what currently exists. The people who benefit from the existing systems would make it impossible for anything else without disrupting power, which, if you view an economy built around profit as something that could not be sustainable into the far future, could be necessary.

This comment isn’t trying to be biased any specific way, just trying to be realistic while also saying alternatives exist but would likely be disruptive for better or for worse.