Why can't Indian uncles and aunties see teenagers having a fun time?

They're always so judgemental when they even see a group of friends of both genders hanging out together. This recently happened to us that when our friendgroup, simply minding our own business, clicking pictures, gossiping about college and stuff and this one uncle walks up to us turns to me and my friend (we're both girls) and he "advices" us to go home apparently because ye sab ladkiyon ko shobha nhi deta itni der raat tak ghumna (it was 7pm) and also he sends dirty looks towards our other two friends(guys)!! (We're all 18 and 19 y/o's btw)