I don't buy shampoo. My shower contains a single bar of soap.
Here in Denver there is a shop where I can buy a reusable glass bottle that they will refill for me when I bring it back to buy more (soap, shampoo, detergent, etc). Perhaps supermarkets could transition to this model for everything.
Ideally bringing the old bottle somewhere to get it refilled.
Yes a nice strong plastic bottle of shampoo that you keep. Wont have branding however or whatever the packaging is supposed to convey for this brand. It will be your own choice of color or look.
Is it not possible to manufacture shampoo in solid form? Like a bar of soap?