> There's no way that anyone in 1937 had congestion in mind when they were creating the taxi medallions
What on earth makes you assert this? The intense and (to modern eyes) borderline insane levels of traffic congestion in NYC at the dawn of the automobile age are very well documented. There are pictures and videos you can easily find, that make today's horrible congestion look bearable and civilized. A lot of traffic rules and devices have their dawn in the same era.
To cite road congestion as being part of the "spirit" of why taxi medallions were created leaves me with the impression of someone being disingenuous.