[xenadu02]

Freight doesn't generally use bypasses or sidings anymore. It's part of the "Precision Scheduled Railroading" movement to optimize operating ratio above all other concerns - mostly because freight train executives and investors believe that railroads are in long-term terminal decline and thus capex spending or going after new customers is a waste of time. (This is a bit glib but not that far from the truth).

Freight in the US optimizes for minimal crew hours. That means longer consists that no longer fit in sidings. Expanding sidings costs money and is thus verboten.

Even if the freight takes 3x as long to get somewhere they can have each crew take a leg then leave the train unattended. The railroad doesn't need to pay for overnight stays or overtime and only one or two crews are "active" in a given segment ever. Or to put it another way the limit is "we are paying for one crew on this segment of the line". Freight lines up on either side as that limit of 1xCrew shuttles whatever they can back and forth within that segment. Then you make the consists longer and longer to "buffer" the bottleneck.

I assume part of the "enforcement" issue is US DOT would need to order the railroad to back trains up or do other nonsensical things that would only create more chaos and delays because as I mentioned most consists can't fit on existing sidings anymore and AFAIK the law has no provision to order the railroads to extend the sidings nor order them to do the physically impossible.