[ahjushi]

"Imaginary" doesn't mean useless or meaningless. Let's take a look at this at a smaller scale: property lines. Assuming one has a front yard within their property lines, that line too is "imaginary" in that it may not be explicitly demarcated or labeled. Would you be fine with anyone and everyone chillin in your front yard? If you want to make the argument that border lines are imaginary, can you even call your front yard "yours"?

We can abolish borders, but that doesn't seem like a future rooted in reality. Who governs who? Sounds like you want everyone to live under one "nation"...like are you really advocating for world peace?

What laws are you subject to? What protections do you have? These are all dependent on which side of the border you land, therefore you have to set where one side ends and where another begins.