Back in the day when I tried my hand at stock car racing for a couple of seasons on a local track owned by the France family, it was explained to me by the track manager that NASCAR is in the entertainment business, not the racing business.

That is also true for most other sanctioning bodies. SCCA would be a notable exception, since SCCA racing does not depend on spectator attendance.

Engineering has been stagnant in most top racing series for many years now as a means to control costs.

F1, NASCAR, Indy Car - all essentially run spec cars.

Thank God NASCAR finally ditched carburetors in favor of fuel injection.