Why is there still hair after hair removal cream?

I'm curious to understand, why is it that despite using hair removal cream, some hair still remains? Could it be that the cream wasn't applied evenly or left on for the recommended time? Or is it a matter of hair type, where certain hair textures are more resistant to the cream's effects? Perhaps there's a chance that the skin area wasn't fully cleansed prior to application, affecting the cream's ability to penetrate? I'm also wondering if the cream's formula might not be suitable for everyone's skin and hair type, resulting in varied results. Clarifying these points would help us understand the science behind hair removal creams and why hair persists despite using them.