If on a flight, you put Dr as your title then you would be expected to be called upon when someone has a heart attack or similar. In this case, if she was approached by cabin crew she would have to admit her title was a wank
What an incredibly ignorant remark - you clearly have no idea what you're talking about. The title "Dr" was used as an academic title way before it was used by medical professionals and is continued to be used in that way. For many careers it would be vital for you to use your proper title or people would assume you don't have a PhD. They absolutely do not expect everyone with the title "doctor" to be able to help with a patient having a heart attack on a plane - that's ridiculous.
You seem to think since you're a doctor no one else has the right to use the title. Sorry that's total rubbish. I wouldn't have made a big deal of it if I was that woman but your comment is so ridiculous I couldn't help replying!