"I wonder why governments subsidize production of commercial airliners so much. There are no network effects or lock-in"

Huge lock-in :)

Aircraft manufacturers are all semi-nationalized they are 'too big' even for private capital to compete on - barriers to entry far too high and too much risk.

Airbus is literally an EU creation. Boeing lives on defence contracts.

So it needs 'a national team playing for it' kind of thing.

There are a lot of jobs, it's very long term, it's big money, involves a lot of tech and R&D so it's a good industry to have if you can get it going. But it doesn't get going without playing 'home team'.