Yes, AS eliminated free standby as it was leading to loss of revenue to people who would book the cheapest flight of the day and then hop on the expensive optimal flight. As of last year it's $25 to confirm a same-day change.

I would probably expect some leniency if I accidentally missed a flight (especially from AS) but it seems like a pretty risky way to try and avoid a $25 change fee, given that they are perfectly within their rights to charge you a $100 change fee plus fare difference for the next flight.