> I’d suspect that the owner values labor in multiples of the minimum

For low-bargaining power labor, having a progression from the minimum is probably a factor; OTOH, UBI eliminates the economic coercion that is a major contributor to low end labor having low bargaining power.

For labor what the combination of oversupply and economic coercion doesn't overwhelm normal market factors, competition among purchasers should result in wages @ the marginal value to the employer added.