Ye goode olde reactive decisions! Put security on the Broadway stations because , , and trains were smashed. They’d never think to trek a block over to 6 Avenue or Lexington Avenue to wreak havoc.
Next thing you know, , , , , and—gasp—even and trains get their windows smashed in. Nobody would ever see that coming. All the data points (1 data point actually) show they only vandalize the yellow bullet trains. (/s)