Az,
Regarding your “just wondering” question its mostly because the guy is the one who does the picking, if he gets a no he picks another and another. While the girl sits there waiting to be picked.
Furthermore because some misguided people have terrified girls into believing that there are 10% more guys than girls (true or not, many are under this impression) thus just the possubilty of a yes is jumped on more than guys who have been told they can be as picky as they want since hey you have a list.
Mostly the first point though