My hunch is that the rules are pretty loose on this. For my IDBs, I didn't hear a peep about VDB in the gate area, but it's entirely possible that a kiosk or counter agent offer was made to someone somewhere...

I've also been on UA flights in recent years where the VDB offer was very weak - it made me think that they were okay moving quickly into IDB-land. One was going to be a six-hour delay leading into a holiday weekend and I never heard the GA move off of $300. In my head, I'm thinking that's worth $750-1000 in United vouchers, or maybe two DBCFREE vouchers, but I never heard where they ended up. I was 1K at the time, seated in F, and didn't stick around in the gate area to see what happened.

Long ago, it seemed like airlines were loathe to IDB. Now it seems like they don't care as much. Government reports the stats, but does anybody look at them or penalize airlines for IDB'ing too much?

Clearly they could have legally (per DOT rules) stuck to the $300, gotten no volunteers, and then IDB'ed people. I don't believe the DOT rules would have said "No, you really have to *try* to get VDB's."