Maintenance teams are discouraged from marking trains and rails for maintenance because delays impact profits.

https://www.propublica.org/article/railroad-safety-union-pacific-csx-bnsf-trains-freight

Bradley Haynes and his colleagues were the last chance Union Pacific had to stop an unsafe train from leaving one of its railyards. Skilled in spotting hidden dangers, the inspectors in Kansas City, Missouri, wrote up so-called “bad orders” to pull defective cars out of assembled trains and send them for repairs.

But on Sept. 18, 2019, the area’s director of maintenance, Andrew Letcher, scolded them for hampering the yard’s ability to move trains on time.

“We’re a transportation company, right? We get paid to move freight. We don’t get paid to work on cars,” he said. “The first thing that I’m getting questioned about right now, every day, is why we’re over 200 bad orders and what we’re doing to get them down. … If I was an inspector on a train,” he continued, “I would probably let some of that nitpicky shit go.”