It's probably because they are more focused on the subject than the technique. We, photographers, look at the technique (in focus, depth of field, composition, exposition...) and we tend to like a photo that it's technically good. We won't really like an out of focus picture. Whereas non-photographers can like blurry images simply because it shows something they like, someone they care about and it's a moment they cherish for example.Its really strange to me the things non photographers like sometimes.
A few days ago I posted a series on Facebook of rozes, one in there was a terrible shot but I put it in because my cat was in it funny. Next thing my aunt tells me that that is the most beautiful pic :S