Yes I understand that part. I was under the impression that any travel agent (i.e. somebody with access to a GDS), can book most fares that ITA matrix spits out. For example, right now i'm looking at flights TYO-BER and matrix consistently finds fares that save me $1000. However, the problem is that none of the OTAs price it for me that way. It seems to me that somebody could start a travel agency (i.e. get access to a GDS), allow my to just enter the specific fare construction and charge me like a $500 commission which I would be happy to pay (since my alternative is paying for something $1000 more. So why does that theoretical agency not exist?