Well, regardless, they (1) wore a collar and (2) were in some kind of official uniform that unmistakably identified them as priests.
No doubt about that. Just not the cassock.
This is ridiculous. In every FSSP parish I have attended the priests are always wearing cassocks.
Same goes for SSPX priests - always cassocks.
The only priests I ever see wearing a black suit with a collar are the N.O. ones.
The practice of wearing black slacks and shirt in public was an innovation in America sometime around the synod of Baltimore (from whence the Catechism), and was commonplace among the Jesuits. Frs. Frederick Schell and Leonard Feeney, both Jesuits by training, did not wear a cassock, but a black suit with a Roman collar. In the case of Fr. Schell, his successors do wear cassocks. At the moment, the successors of Fr. Feeney do not include priests, but the Brothers M.I.C.M. wear cassocks.
Fr. Hector Bolduc wore a black suit with Roman collar, as did Fr. Fiore and Fr. Malachi Martin.
You shouldn't forget that all across America "The Blackrobes" meant one thing, even to the Indians. The American Martyrs, St. Isaac Jogues and Companions, wore black cassocks.
From what I hear, it is being recognized that the gradual change from cassock to suit had been a subtlety that had seemed okay at the time, but in retrospect carries a much more significant burden and connotation, to the effect that it is worth re-examination.
.