I haven't cut every cake in the world but I know they can all be cut in to eight slices

360 degrees is essentially an "arbitrary" mathematical decision to split a circle in to a number of even parts. We know that the number "360" exists, and we know a concept of "equal" so we know can make 360 equal divisions...

If we take three cities which are each on consecutive latitude lines, 30, 45, and 60 degrees: the question is not whether those lines are an equal distance apart, the question is are those cities actually on those points and are those cities an equal distance apart.

So yeah if those distances are in doubt then the way they constructed the graph is in doubt, however i would suspect that if you start with the opposite assumption, and assume that all the lines should intersect, then that would give you a "ratio" of distance between different spots on the earth. I suppose as the OP i have to go away and do that work myself dont I lol argh i can't really be bothered... Anyone else? But I'm assuming it's going to show us things like "the distance between france and london is the same as london to new york".... and us REers will say "that's crazy, we know thats not true, the world is not flat" and the FEers will assumedly say "well we know the world is flat, so that must be the true distance", if we get to THAT point... then we can begin to construct a flat earth based on those distances right? (at which point i'm guessing the FE will just say "how do we know those original measurements were correct"...

It would really help if there was a consensus between flat earthers about an acceptable method to measure distance, and thanks Edby for proposing the triangulation method... That's the sort of thing yall need to agree on, and then go out and do. That would require quite a bit of time though so I'm thinking it will be hard to get off the ground. There's no point RE doing the work as it won't be believed