Why is the quote "There was one odd thing, though, that I never understood: in spite of Atticus's shortcomings as a parent, people were content to...

At
this point in the book,is trying to figure out how to feel about the trial. Everyone in town
talked about it and saw 's defense of Tom Robinson as a kind of moral failing. While Scout
andare not blamed ("neither of us could help having Atticus for a parent") the trial
and the ugly feelings it stirred hangs over the Finch family "like smoke."

The quotation you mention points out an inconsistency in the town's attitude toward
Atticus. The fact that he is reelected to the state legislature "as usual" suggests
that people are able to feel prejudice against blacks while at the same time recognizing Atticus
as worthy of representing them.

It is like the story that immediately follows
of how Miss Gates can hate Hitler's persecution of the Jews while at the same time approving the
verdict against Tom. Scout is confused about how people can think two different things at the
same time.