In all honesty, getting rejected always stings a little. It can leave you feeling a little disorientated and even devastated. In some cases, people can get mad and if they have mental issues, they will go for stalking you or something like that. I can see why some ladies would prefer not to respond to a question of asking her out. I think it's pretty much safe to say it's because she wants to say no.
There's a point in time, you are just going to have to give up even though I had a girl who was reading and not replying to my messages, eventually write back to me and ask for a favor in exchange to do something for me. I pretty much shut her down but then years later, I just wrote again asking her out since I remember having this physical attraction when I first laid eyes on her.
She went back to just reading and not responding. I don't actually know anymore, but I'm going to assume it's a sad no from her, but still a no which really doesn't matter in the first place. It's crazy but when a girl says no to me now, then I don't think it really even matters. I'm still going to play it like a gentleman even if I want to scream out insults from the top of my head! This could very well be why some hot ladies don't respond because they don't want to tick off guys who could become mean and scary from not liking them. Also, if a hot lady doesn't respond, isn't she worried that a guy is going to stalk her? Wow, this one lady is uncertain but I'm going to have to guess it's going to be a friendly no and time to move on.