I believe there is a speed limiter on modern revolving doors. If I recall correctly it is a "paddle in oil" arrangement whose resistance force is a 4th power of speed.

I do not know why I think I know this, but it seems to be true: http://www.internationalrevolvingdoors.com/IrdManualDoors.ht...

As for "why", I'm sure fast doors both scare people and attract lawyers.