I actually work in a doctors office. I'm not a nurse or anything, just an assistant, and my boss is pretty chill and allows my hair as long as its a normal color. I have it up everyday at work. Plus,because i work in a childrens office, little kids love seeing it.
the only job I was out right refused an application (and my hair wasn't up or anything, just a curly fluffy mess) was for a shitty pet store (which is illegal - based upon discrimination)
however, when I showed up three days later with my hat on and my letterman they were more than happy to give me an application.
I also interview a lot, for jobs I don't intend on taking. It's good practice. No one has ever had an issue through the interview process.
I'm a computer programmer that sub-contracts for the department of defense. I work from home and the only time they see me is on webcam so they really don't give me a hard time. Sometimes I do have to go on site (military bases) to work, but I haven't been questioned about my hair or ears so far.