As noted in links provided above Swash detergent was in partnership with Amazon, and latter was sole vendor. Well at least according to press announcements, haven't seen Swash at local WP appliance dealers.
You can find the stuff on fleaPay, but Amazon moves goods via that platform as well.
There are versions of Tide seemingly only found at Target or on Amazon, so it doesn't surprise me WP came out with their own product. Miele for some time now has their own laundry product range, and given Whirlpool's market position they can easily do same.
In partnering with Amazon WP also can from bottom up design packaging that will survive shipping/delivery.
Huge issue with liquid laundry products and others is they break open, caps come off, contents leak. Amazon is dinged for this constantly. P&G among others have developed new types of packaging for their liquid products that supposedly minimizes risk.