@Derael
Not that I have any personal experience, but I have read about it in a few places. Apparently blonde is one of the least liked colors for hair in terms of professionalism. If I had to make a comparison, it would seem to be similar to how if she had bright pink or neon green here in the states. And while a lot of companies now are more or less accepting hair color as irreverent, many larger corporations with a "professional" public image do still require more natural hair colors. I knew a friend who had really light natural blonde hair (platinum blonde). She had to at least make it a bit darker shade of blonde when she got accepted into her job. She was not required to do it since it was her natural hair color, but it was heavily suggested so she could keep a more professional appearance. Same thing happens for people with noticeable tattoos, piercings, ect... It is fairly common for businesses, especially larger, older corporations, tend to desire the default human skin.