While Interstate was created by a professional type designer, it is based on Standard Highway Alphabets commonly referred to as Highway Gothic, which was never designed by a professional type designer.
The original typographic definition of "kern" referred to a portion of a letter on a metal type body that was left to protrude off of the type body and be supported by an adjacent type body allowing for the optical space between the two types to be reduced.
So while it didn't happen very often in metal/letterpress, it did exist. I remember cutting kerns on type when I was a letterpress student at college. Pain in the ass does not come close to describing the process.