First, I think the reason that you don't have exchanges at TMEA auditions is pretty obvious. But as for TSSEC, I think those conversations take place as a quick attempt at recruitment. Professors might keep in contact with a director if they hear a number of good musicians from them. They may pay them a visit down the road. Some kids are still on the fence in choosing a school and they will make a quick pitch. Some are just looking for musicians even if they aren't music majors. That has been my experience.