Some problems with your perception of American academia:
Ability to publish gets you to the interview stage, the rest is good old-fashioned politics.
Adjuncts are still expected to publish, unless they have no interest at all in upward mobility.
Of course the structure is suboptimal, but no one's really come up with a better alternative.
I think you have confused adjuncts for "lecture" positions or other "visiting" faculty.
Generally, adjuncts are (very) low paid contract workers- maybe $2k-3k for a 4 credit course who are not expected to publish (they generally have little to no access to university research resources, not even an office on campus!, so publishing is largely impossible) and have no real upward mobility. Most adjuncts work some other full time job (they have to- a full adjunct load generally pays less than 20k a year). These positions aren't supposed...
Another month, another rationality quotes thread. The rules are: