Its really all one in the same.
I think its more because plastic surgery is considered a medical procedure, and steroids are demonized as a drug.
When the reality is theyre all done in the pursuit of vanity and both have possible health complications.
My opinion is, let people do whatever the eff they want with their body. But as long as we have the 'war on drugs', steroids are an easy target to sell to the public, and its easier to look like theyre making a dent vs REAL drugs like Meth, Heroine, etc.