What about the investment in fuel, energy, water, and detergents: to collect the reusable containers, bring them to a sorting facility, sort them, bring them to the manufacturer, and wash them before they can be refilled?

Disposable containers are much lighter and cheaper since they don't need to be so durable for repeated washing and filling. The additional fuel costs of shipping heavier reusable containers around must be pretty substantial in itself, let alone all of the other steps.