White leather shoes, fashion or uniform?

[Sgt. Ian MacBrooke]

I have watched The Knick, a new victorian era piece about the Knickerbocker Hospital in NYC and the interactions between the doctors, nurses, management and even the ambulance drivers. Feels kind of like House only victorian. The question I've got is the main character, Doctor Thackery and the doc he replaces are wearing white shoes. Is it fashion or uniform? I await any answers...