You are right about girls who go out with guys but never want to
progress further than just being ordinary friends.
Usually, if a guy is interested in a girl, he will ask her out
as often as he can. Very rarely will he ask a girl out many
times if he is not interested in her in the BGR way.
On the other hand, girls may not be looking for a relationship
whenever they go out with guys.
A girl will feel flattered that she is the target of a guy's
attraction, and as such, she may consider going out with him
occassionally just to "hang out" . There is perhaps an ego
thing at work here.
So there is a big difference in general, how guys and girls
behave with respect to "asking the other party out" 
You see, it doesnt have to mean a guy confirm must get the girl
just because he asked her out. Yes, he could be interested,
assuming there is interest. It could be he's exploring the
characteristics of the girl and how she is compatible with him or
whether she will bring excess baggage. If your boss interviews you,
he cannot simply make a decision immediately to hire you unless he
is desperate. He has to consider whether you are suitable for the
job and how capable you are.
So you see, it doesn't mean he's damn interested in the girl and
must get her at all costs. Heck, he could even lose interest after
a few dates.The same could happen to girls. After all, this is
human nature. We lose interest due to some X reason. But I'd say
girls change interest like the flick of a switch more often than
guys.
And we have the case of the girl going out with the guy even
though she knows she wants nothing romantic out of this. This is
where the confusion begins. Here the guy wants a relationship and
the girl knowing this, as most girls do, leads him on and at the
end of the day, tells him, "I just want to be friends, dear".
It's just plain sick and disheartening to hear such stories
happening because this is really selfish on the part of the girl.
But of course, reality sometimes hurts and we have to be prepared
that such people exists.
