Why aren't the Chinese and Russians successful at building airliners? International politics aside, they have workable products, so why can't they break into the duopoly.
Workable != competitive, and in an industry as cutthroat in aviation airlines want the absolute best in fuel efficiency and reliability to undercut their competitors by $5.
There are other commercial aircraft manufacturers but essentially in each size segment you will only see two players. Embraer doesn‘t make any direct competitors with Airbus or Boeing, as an example.
Embraer jets got rebranded as A220s not that long ago, great planes that took over the market that served by short 737s and A319/18s. No competition for the bigger planes, that is true.
