The fact that the middle shelf of a supermarket is usually the first one to be empty is quite compelling evidence.

> I guess it’s your first time buying detergent it might work but most people I know have a specific detergent and they buy the same one no matter where on the shelf it moves.

Just to validate that assumption: Would you say this is the same for toilet paper? Soap? garbage bags? Sponges? Pencils? cooking-oil?

There are lots of commodity items I use where I don't know the brand, I cannot even tell how often I switched the supplier of them in the past year...

Subjectively, most people _I_ know buy out of a pool of detergent-brands, all looking quite similar (and most belonging to the same parent company). If they are bombarded with advertisement inside and outside of the shop, and maybe a stacked palette of a different brand of detergent, many of them will "try" this new product instead and end up expanding their pool of brands they will buy.