that's not some universal truth, that's a loss-reduction scheme that certain live event ticket sales groups adhere to.

In some cases it isn't even loss-reduction, it's just a means to increase profit; there may not be a loss associated with refunding a ticket to a venue that isn't sold out and has unassigned seating other than some virtual infrastructure loss like "they used the bandwidth of our service without creating a profit this session ", which is basically the equivalent of a restocking fee at a small pawnshop where an already hourly (otherwise idle) paid employee just throws the product back on a shelf (aka : bullshit).