I think the thing is that there are people from north of the line, and people from south of the line. If you are either of these people, your opinion doesnt matter. Its all about the people who grew up or decided to live on the line. These people get to decide if there is a border or not.
If someone puts a dividing line in my back yard, you bet i wont respect it. It would be duty to erase it.
Border walls. Lol. Take a fraction of that time and effort and dedicate it towards education, we would all be one better off family.