Even the newest kid on the natural hair block has been told about how bad Mineral Oil is for our hair. I have been asked in the past why Manufacturers still put it in products. The simple answers are:
1. It is cheap.
2. It is non-greasy.
3. It is predictable.
I bet you understand the first 2 reasons so let me spend sometime explaining the last reason.
Mineral Oil all over the world can be made to a certain specification. However, natural oils aren't. They simply cannot be. The quality of soil, geography, cultivation method means that the very same Oil (say Castor Oil) may vary in property from one country to another. In fact, it may vary from one area to another within the same country.
A good example is our local Udala fruit (Igbo). It is also known as Agbalumo (Yoruba). If you eat the one from nearby Republique Du Benin it is almost always sweet. However, the same fruit grown in Nigeria may either be slightly sweet or remarkably sour.
From a manufacturing point of view, this means that a product made with natural products may not always turn out exactly the same. To reduce some of that variability which consumers do not like, manufacturers will stick to something like Mineral Oil which gives exactly the same result every time.
J. Serb. Chem. Soc. 75 (3) 343–348 (2010)