There's a number of reasons (from logistical to legal) as to why network services aren't available outside of Japan (and some other asian countries in certain instances), but it fundamentally comes down to that there's little to gain for the companies to set up the infrastructure required for said services to work in other parts of the world.
There are a couple of places where you can play BBCF in the US and that is a special circumstance, as those are all Round 1s in the US. They can do it because... honestly, they're one of the biggest vendors for all of the arcade game producers in Japan and they were looking to expand internationally, so they had the clout to work something out. Even then, it's rather limited as the Nesica cabinets in the US have only BBCPEX, BBCF and USF4. (To my knowledge, R1 still has to license out each game individually for use internationally, as most games don't have any negotiated rights for use outside of Asia with possible license holders). There's also the fun fact that both Nesica and e-amusement (Konami's network, which R1 has access to as well) go into maintenance during the evening in the US. (Why the networks need maintenance every night, who knows.)