They're run out of the alumni center, not admissions. I would guess at least 75% of golf cart tours are to people who attended BYU. If BYU wanted to treat these as a recruiting tool I'm sure it would become something phenomenal, but that's not how BYU sees them.

Most major universities are in competition with others for the same students. BYU is not worried about that and they subsidize tuition for every admitted student, so decision makers have chosen to focus almost entirely on the "show us why you belong here" side of things.