I think it's called med compliance because it's a standard rule of "take 1 pill once daily" or whatnot. That's the presciption, and not following the prescription's rule can have negative consequences - overdoses or withdrawal symptoms and all sorts in between.
I don't think of it as complying to anyone's will; I view it as following the rules for safety's sake. Just like I will comply and follow road safety rules and I will comply with the firecode to ensure that my classroom isn't a firehazard. It's all about safety, not about someone else's supposed authority.
If I comply with the prescription then I should see the results that I am wanting/expecting. If I don't comply with the prescription then I will probably end up with results that I am not wanting/expecting.
I guess I view the word "compliance" in a totally different light than you eh?!