This was a couple of years ago.
Issue: Colleague and I, both in fully flexible J, both Plats arrive at QF SFO check in for flight to Australia on QF metal. We had arrived off an Air Canada connection, which was late. We arrived at check in thinking we had made it, although right at the end of check in time. We thought QF would know that the AC flight had landed and we would be on our way (the AC flight is shown under our bookings, at least on what we can see on line under 'Your bookings' - I assume QF staff can see at least as much).
When we arrived, there was one pax there being checked in (bag on scale, BP being issued); there was no 'flight closed' or similar sign illuminated. When we came to the counter, there was obviously some issue as we handed over our passports (the check in guys looked at each other...). We were never told that the flight was closed, as it clearly wasn't, but there was a call made and we were immediately offered accommodation, meals and US$500 voucher if we agreed to go on the next day's flight. Else they could get one of us on in J and one in Y on the current flight. To be honest, neither of us were in a hurry and an extra day in SFO on Qantas appealed. So we readily accepted the offer and didn't grill them as to what the heck was going on.
We assumed that they had bumped us, assuming we weren't going to show, but were caught out when we showed at the last minute. And yes, we were within the checking-in time window.
Outcome: For partly 'voluntary' off-loading till the next day's flight, strongly suspected to be a mistake by the check in staff: US$500 voucher, re-imbursement of decent airport hotel room, re-imbursement of meals taken at the hotel. An added bonus was that since it was a voucher issued in the US, it was redeemable for cash
Satisfied, but would have been vastly different attitude if we weren't so relaxed about the timing and if SFO wasn't such a nice place to goof off in.