Yeah Jay, it is definitely challenging everywhere, but like you say there are no actual restrictions. A surgeon can decide not to operate on someone under 18 for their own reasons, but plenty will still do so. I actually contacted Dr Medalie and another surgeon who's name I now forget and they were willing to operate on me but my mother wasn't happy with me spending all the money that is meant to go towards a good university degree on surgery and flights when we are covered by insurance in Australia (I know I am very lucky to have this money here in the first place). It isn't challenging to get surgery in the USA if you are willing/able to travel and have full parental support. I have seen people who have had their surgery and are able to get on with their lives at 15 (I am older btw).
In Australia there are competency laws, so the surgeon has to believe that someone under 18 is capable of giving consent, AND the surgeon has to be willing to take the additional legal risk of the operation (obviously I take full responsibilities for my actions and the idea of me regretting this surgery is laughable, but there have been a couple of "I changed my mind" lawsuits involving people over 18 here, and if a surgeon operates on a minor regardless of competency the individual would have a stronger case in court if a lawsuit were to happen). Considering how few people routinely perform this operation in Australia, Dr Hassall is the only person who fits this criteria. She does some amazing work but I feel the big, perfectly straight nipple line scars bring more attention to the area than a scar in line with your pec muscles, and I have to wait more than a year for the op at a time when I should be focusing on graduating school with good grades.