Have you ever noticed at the pump that the nozzle for diesel doesn't fit in your car if it uses a gasoline engine? Try it some time. This is to prevent people w

Have you ever noticed at the pump that the nozzle for diesel doesn't fit in your car if it uses a gasoline engine? Try it some time. This is to prevent people who aren't paying enough attention from ruining their day by putting diesel in their car. It would be trivial to sell large commerical-grade detergent containers with similar protections to provide an affordable, fool-proof mechanism to refill their own cannisters. The best thing about this approach is that you could still provide the subscription based model to anyone who truly values the model (instead of being simply forced to use that model due to lack of a suitable alternative), giving your customers the best of all worlds. Obviously, that doesn't quite rake in the money the way that the "razor and blades" approach to gouging your customers in the name of convenience does. Obviously anything that means you rake in less money is against the short-term interests of the sales department, but not necessarily the long-term interests of the company.