1. The company say's being eco friendly is important to them.
2. They manufacture, sell, and ship expensive plastic containers for their detergent.
3. The machines don't necessarily need this specific detergent, and will work fine by leaving in one of the "cassettes" and just using normal dish detergent.
This means that the cassettes were never necessary, and are purely a separate stream of income for the company. Literally the printer ink method.
Which means they didn't have to produce this plastic waste at all, they could have just allowed it to use a smaller amount of liquid or powder detergent (pre-portioned pods are probably too much detergent).
Hell even if they wanted to continue with the printer ink approach, they could have used powder detergent in little wax-lined cardboard containers.
Regardless of how well they're recycling or re-using the cassettes returned to them, the cassettes never needed to exist. It's more plastic taking up more space in more polluting delivery trucks.
At the end of the day this company is selling a dishwasher and a detergent subscription service. It's not the worst thing out there and it's not creating nearly as much plastic waste as the fishing industry but it's still a company greenwashing itself to sell you more garbage.