Putting station walls behind handrails, out of reach of graffiti "artistes", also helps.

Coping mechanisms always astonish me. No, it is not normal to lose function (passengers/square feet) over uncivil behavior.

The DC metro stations are very spacious. Been a long while since I lived in DC but they weren't crowded compared to stations in NYC or London.

It was specifically a Great Society program meant to contrast with Soviet metros and their ornate architecture. NYC and London have the issue where they were first generation systems trying to figure out what worked and what did not.

DC’s general height limits in conjunction with typical American SFH friendly zoning also do not help utilization.

1) It's not a cope, it's a compromise.

2) It's not uncivil, it's illegal.

What is so astonishing, and what is your alternative to this specific issue?

That’s america in a nutshell. We can’t infringe on people’s precious individual expression and self actualization after all. That said in the DC system, expense was traded off in favor of cleanliness and lack of crowding—the stations are enormous (and very costly).