That's because it's been done, and subsequently ignored. Especially distances across continents are known... by people who drive a lot or who drive high-speed trains... it gets done in an approximate fashion every day.
So no bud, it isn't equally likely, but one does have to believe the readings on milometers and spedometers, and if one claims that these readings are all fake, and requires me to design and build my own instrument then it becomes impractical.
The stars and things are all conclusive proof of non-flatness but you glibly ignore those or befuddle them. So one has to suggest experiments where you then pull out the "you can't make me, and if you can't do it, and if someone else does, its fake" card.
It isn't clever, it's like the kid at school who looks the other way and sticks his fingers in his ears and then claims not to have heard what you said.