Pros and cons for closed try outs, well there is a question that is sure to evoke plenty of debate.
I couldn't see too many people agreeing on one or the other, it will be mixed. I have been on both sides at rep try outs, selector/coach and parent.
If closed try outs are so parents don't argue about who didn't make a team, wrong, that doesn't work.
If it is to make people feel like they are not trusted to watch and the coaches appear to be snobs, yes, there is an element of this for sure.
If it is to just avoid parents and questions until try outs are over and teams selected, then yes, again that one works a treat.
There could be a number of other reasons, I for one don't think either way is better than another, however closed sessions for rep' smack of a lack of self confidence in the coaches (perhaps fearful of any criticism) and it builds an appearance of hiding something on the Association's behalf.