Some of these folks are very serious about testing.
With attempting to run straight, you might get a super run once in 30 runs.
With proper rail running, you get a very tight distribution that beats 97% of the straight runs.
If you look at the videos, you might see how to get almost NO added friction from how you set up. You are going to get friction as you roll down the track. If you contact very near the bottom of the wheel against the rail, you roll against it without adding friction. Every time a straight car hits the rail, even the front wheels, they lose energy big time because they grind into the rail at an angle that produces more friction in a few bumps than you get with rolling all the way.
Many of these builders have built a car as you describe early in their racing days. They won- they came here- they lost to rail running.