For me as a travel agent this is not news, but I sometimes still fall into this trap! Our computers are programmed to ticket the lowest price possible for a given itinerary and I can't recall how often I had to void a ticket because I had let my system issue a restricted Y ticket while unrestricted Y would have been just 10 EUR or so more. To do so, we have to manually override the best price option, which can easily get overlooked. Just one more example of absolutely weird airline pricing...