In the beginning the ICC policy made some sense because the railroads were hugely profitable monopolies, and public utility theory supports the concept of the money making parts of a monopoly supporting "needed" services to the unprofitable customers....this is the origin of "plublic convenience and necessity". But the motor carriers not only destroyed the railroad monopoly but they stole much of the most profitable traffic. And the ICC failed to adapt its policies to those changes. But railroad management was also at fault. Because of the regulatory constraints management became bureaucratic and embraced regulation to justify its own underperformance. And as noted above the Staggers Act changed all that.
JBWX