The reason planes don't fly straight across the Atlantic is due to math and physics.
Planes don't fly straight across the Atlantic because the circumference of the Earth is a lot further around the equator than it is at higher or lower latitudes towards the poles of the earth, such is the spherical shape of our planet.
Flying around the smaller circumference of the Earth is called the “Great Circle Route” and also very noticeable for flights from the U.S. to Asia that will fly far above Alaska and Siberia rather than what would appear to be a straight line.
If you think about drawing a line around a globe in the middle where it is widest, versus towards the North or South poles, the differentiation of distance begins to become apparent, and it not only saves a huge amount of time but also fuel.
It makes much more sense to not fly straight across the Atlantic.