For a start, corporations are very small compared to states. Even Walmart, the world's biggest employer, is less than 1% the size of the US by headcount.
More problematic is that corporations plan to maximize profit. That's it. It's a comparatively trivial optimization goal compared to the multitude of ways of valuing things that exist in wider society - and yet, corporations still frequently fail to be profitable. OP's example about the wedding ring is a case in point. Walmart's Finance department would value that for its raw weight in gold only.
But even more worrying, corporations have a magic tool for maintaining order and efficiency: firing people. States can't do that, or at least, not states that you'd want to live in. Corporations are rigidly hierarchical. Corporations are not democracies. Imagine human rights as implemented by the HR department. Scaling up corporate processes to manage a whole country would result in a terrifying dystopia.