my question isn't silly? The shortest route between 2 points is a straight line. I assume airlines realise this and don't want to burn their profits by way of flying longer distances.
Uhh okay? Well I guess I'll answer your question then.
If you support RET: What you're seeing is a direct path on a spherical surface represented on a flat surface.
If you support FET: You're using the wrong map, the continents are radially situated about the north pole.
Welcome to the board, enjoy your stay.