Please don't go around spreading false information like "all shampoo is made with lye." I think you are confusing melt & pour soap with syndets. Yes, M&P soap based is originally created using lye, but syndets are a completely different product.Next, ALL soaps are lye based. So are shampoos. They ALLLLLL lye based. You can look up no-lye soap recipes, but they aren't that effective, used supposidly by extremely sensitive people. I don't know anyone who has tried these recipes actually. Commercial soaps sold in stores are ALL lye based. You can look this up. This is not a secret. The comments on here are just bizarre about lye being a big scary thing that nobody uses on hair ever oooooooo!
Today, most commercial shampoos, laundry detergents, dish detergents, and dishwasher detergents are made with synthetic detergents (syndets). They do not contain actual soap, and were not made with lye. My handcrafted solid shampoo bars also contain no soap, only syndets, and thus were not made with lye.
I washed my hair with soap for years, and it was fine. However, since I quit using soap bars for shampoo, and started making and using syndet bars, my hair is much more soft, less dry, and more manageable.
To be clear, I agree that lye isn't the issue, since no lye remains in properly finished soap. The issue for many people is that the pH of soap is too high, and it dries out their hair terribly. The example of folks using soap to wash their hair in years past isn't comparing apples to apples, because most folks today wash their hair much more frequently than folks in earlier times. The high pH that didn't bother folks who washed their hair once every couple of weeks, is much more damaging when one washes that same hair almost daily.