I’m taking a shower at someone else’s house and I noticed they have 1 bottle that says “3-in-1, shampoo, conditioner, and body wash”.
Why isn’t this the standard? Why do we even need 3 different types of soaps to bathe?? Have I bought into Big Soap capitalist propaganda without even noticing??
I just finished showering with the 3-1 soap and I don’t feel any difference between the 1 soap vs the 3 soaps I have at home.
Shelf space.
That is, filling the shelves at the supermarket with the illusion of choice. Manufactures want the most shelf space they can get so that you spend the most time looking at their product, but a huge shelf of the same product is also a turn off, so variations of a products are churned out. E.g. sensitive, no fragrance, varied fragrances, coloured hair, curly hair, 2in1, 3in1, pre-rinse, post-rinse, ad infinitum.
This is not intended to invalidate all the other replies talking about some of the technical differences (real or perceived).