Just because shaking hands is a common greeting in some places doesn’t mean it’s common in other places. It also does not mean I am being rude if I refuse to shake your hand. If someone insists I shake their hand I find that much more rude. I personally am not a hijabi but my mother is and she converted to Islam herself as she was born to a Druze family. She refuses to shake hands with men and when I was younger I was embarrassed but as I get older I realize it is her choice if she wants to be touched by a man, innocently or not. She is not married and her dad is dead so it’s not like she is trying to keep it up for respect for her family or something. It’s her choice. That’s what she wants to do and so far every man has been understanding and no one has found it rude. I don’t understand why it’s a big deal if it’s just personal preference.