I don't really understand this procedure. Every flight (not many) that I have booked for, I have got on and traveled. I suppose that over booking takes place because of no shows and/or perhaps cancellations. It seems to me that a no show should lose the fare money...if they do not already. A voucher should be given for a late arriving connecting flights so that this fare would not be lost to the passenger. A reasonable amount of time should be allowed for (by the passenger) at the connection, in view of uncertainties involved
Cancellation less than a certain period of time before the flight, might be a fare forfeit. At the last minute the gate is closed and stand by passengers fill any empty seats...whats not to like; they might be paid for twice.
There will always be the occasional emergency though...that's life. I am pretty sure that the Galapagos trip will be made good.