I would want the "auto-add" to be optional/configurable. I would set it to notify everyone on the wait list that court has opened up and they can book it first come, first served. Even if someone puts their name on the waitlist doesn't mean they still want the court 4 days later if it happens to open up. People make other plans.

We would find something like this useful.  Even better if we didn't have to have any event to debit their package balance.  

I posted a related feature request here:

Allow packages (punch cards) to be debited when checking in at kiosk for unscheduled drop in play.

We would really like to see this feature added to help our operations for all the obvious reasons.  Thank you!