Why can't southerners understand the jokes of Northeasters?

It should be because of the cultural differences between north and south.

The reason for this situation should be the cultural differences between the two, as well as the differences in living habits and ways of doing things.

Southerners refer to people who live in areas or countries south of specific or implied bearing points. In China, it refers to the Yangtze River basin and its south area.

Northeasters, that is, the northeast ethnic group (this concept does not apply to all residents in the northeast), while there are other ethnic groups in the northeast, such as Jiaoliao ethnic group and Luji ethnic group. Generally speaking, the nationalities in Northeast China have a greater sense of identity with the concept of "Northeasters" than with their respective provincial administrative regions. Northeasters are based on the concept of cultural and historical identity, not on the concept of regional formation.