I haven't used shampoo for years, just use soap.
But yes, I work in a business that supplies the shampoo manufacturers and I can tell you that shampoo is much of a muchness, basically surfactants and foam boosters, preservative and other "aesthetic" ingredients. Here's a simple shampoo formulation:
Sodium Laureth Sulphate Detergent 45.00%
Cocamide DEA Foam Booster 3.00
Deionised Water Carrier 51.30
Methylchloroiso
Thiazolinone &Methylisothiazolinone Preservative 0.20
Salt Thickening Aid q.s.
Citric Acid pH Adjuster Sufficient to pH 6.5 to 7.0
Fragrance Perfume 0.50
You can also add colour, pearliser or opacifier, silicones and other things to improve the hair feel and even an extract or two, which is nothing more than water and propylene glycol, which has had some aloe vera or summat soaked it it, added to the shampoo at 0.2% to support the fancy label claims. Dress it up a bit, pack it nicely, charge a high price, advertise it on the telly and you can fool most of the public into thinking it's better than the others.