The situation is very different in USA compared to Europe where different attitudes prevail. I've never had a problem with standby in the US. If a seat is spare, they will get you in to it, irrespective of fare class. Compare this with Europe, where it is very difficult to standby on cheap fares, except by paying a fee.

As an example, I had a situation recently flying from Munich to London on an LH cheap fare. My meeting finished earlier than expected, so with nothing better to do I went to the airport, prepared to hang around. As it happened I arrived in time to make an earlier flight, and asked if I could standby. The ticket agent said the earlier flight was wide open and if I paid a 50 euro fee I was OK to go. This was despite the fact that the later flight I was booked on was full. As the 50 euro would have come out of my pocket, I chose not to 'standby'. I understand this policy is to encourage PAX to buy more expensive flexible tickets. The downside on this occasion may have been that a full fare PAX may have been denied standby on the later flight!