I think if anyone wanted something bad enough and puts an effort to getting it, they will get it. But if one goes in unsure or intimidated, chances are they are only gonna get burnt.
So you went in there like a lamb and got no where but your man went in there like a man and got what he wanted.
My mother is 5'10" tall and not a small woman by any means and she has never had a problem getting what she wanted or putting her point across.
My wife on the other hand is only about 5'1" tall but, she gets what she wants and puts her point across also because she knows how to after all her years.
Just be sure of yourself and don't be intimidated and you will most likely not be overlooked.
And as sad as it is going to sound to you, it also helps to have big tits or a big ass or both and a bigger, meaner, louder mouth to match.