Yes I agree…Holy Quran mentions the virgin Birth in contrast of Jesus AS. Similarly it does not reject that such incidents can or cannot happen ie something which is precisely unknown to us. This situation is quiet similar to when Allah says he sent 124000 Prophet to various parts of the Earth for mankind but it only mentions the name of very few. But it does not say that Allah has only sent the Prophets he named. Similarly the Holy Quran is empty with the word that only Jesus AS was born from a Virgin.
Now to your second part…as you said at the moment we do not have any such evidence. I agree there is no such evidence but stamping on the fact that it cannot happen at all then let me tell you people never thought about flying or going to moon but they do now. However this should not be taken as my conclusion on the topic.
Apart from Budha and Jesus I have come accross few more stories where people have declared Virgin Births.