In the linked video they claim the powder washes better (in addition to the environmental benefits) even at 30°. Also the cardboard boxes for milk DO have a plastic lining, but it’s not secret. Otherwise the liquid would destroy the cardboard. But this is OK I think, it gets collected and partially recycled. The “bad” microplastics are inside the liquid detergent itself, to ensure that soap and water remain well uniformly mixed.

Mines are quiite heavy, you would need some big ass drones. And usually mines are hid under a layer of soil, just having them lie around would make it very easy to dispose of them.