YSK if you are in the U.S. and have health insurance through your employer, there's a 2/3 chance that your employer dictates what's covered and not covered - not the health insurance company.
from /r/YouShouldKnow
YSK如果你在美国，并通过你的雇主购买医疗保险，有2/3的机会你的雇主决定了什么是承保和不承保--而不是医疗保险公司。