From my own perspective, riding sports bikes on the road predominantly for the majority of my riding journey, body positioning wise i was always right up on the tank.
Then getting into doing track days and having help from instructors and youtube haha, when you actually get your body into the correct position for hanging off, it feels totally exaggerated and foreign and yes quite uncomfortable for a long time.
For me, i definitely wasn't flexible enough so i stretch religiously now, having a crash and breaking my pelvis in 2013 didn't help and its been tough i have to admit, particularly for me getting me hips turned into the corner so it's a work in progress.
And it still feels foreign at the moment.
These pros don't really ride on the road and i would think they started when they were kids and have been shown the proper position right from the start so it's just second nature to them whereas for me it's not.
Just my 2c!