People who hold collective responsibility

When a heinous crime occurs in Gwangju,
"Yeah... it's those Jeolla-do communists."
When an incident happens in Daegu,
"As expected, it's just so typical of Daegu."
There are many conservatives in Gwangju,
and many progressives in Daegu too.
I don't understand why people generalize like that.
Is a daughter a bitch if a mother only gives birth to girls,
and a bitch if she only gives birth to boys?
Please, let's stop grouping common sense and rationality into specific groups.
I am not from Daegu, Gwangju, Gyeongsan, nor am I a leper or a Jeolla-do thug.