Given that there's no production overhead involved, it doesn't seem entirely necessary to flood the program with a full slate of American style advertising as if it were.
From the standpoint of the BBC, this is probably gravy to some extent.
True. Just like The Good Wife
running in Qatar would be gravy to their studio. But these factors are taken into account even well before a project is even green-lighted; if a project is not expected to do well overseas it has more of a problem getting on or staying on the air in the US, and vice versa.
Also, how many commercials they insert is not based on how cheap something might or not might be to produce, it it based on whatever the traffic will bear. They want every nickel, regardless of how much of it is gravy.
From the point of view of the networks (unless they also own the production house) and the stations, production overhead is already factored out of every show; that is already rolled into the cost per ep.
But there is always overhead; getting that product to viewers is costly by anyone's yardstick. Satellites are easily 50 mil not including launch fees, fiber goes for thousands per month. Engineering support (thankfully) and infrastructure will always be needed. The only way around that it the internet, which has overhead of its own. But that currently does not have access to the multitude of eyeballs accessible by cable, sat, and OTA. At least for a few more years.