system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is shampoo usually translucent but conditioner opaque?
gpt
Because conditioner is marketed as a "cream". (In fact it's sometimes the case and used to be the case back in the day that people would call conditioner "cream rinse".) 

We associate opacity with creaminess and moisturizing properties, while we associate clarity with cleaning properties. 

Kind of like why Crystal Pepsi didn't do well as a product, and why the SNL spoof commercial for "Crystal Gravy" was so hilarious.

TL;DR It's all marketing/what we expect the product to look like.