When I try to create a hair simulation in blender 2.82, the emitter object falls to the plane, but the hair doesn't follow.
That's a (known) bug: https://developer.blender.org/T75105
The Particle System is being replaced, so until then (hopefully 2.90) we will have to live with this...
The fix was provided by Zijun Zhou at https://developer.blender.org/T58044 back in Sep 2019, so am guessing it was there in 2.8 or 2.9 alpha
In 2.91 today, this can be fixed if Collision Settings on the active rigid body is set to the following
Shape = Mesh; Source = Base.
That's not really a fix, just a workaround. Bug still exists in 2.93. Will probably be fixed with 'Everything Nodes'.
Don't get me wrong, it's a good workaround, but it's just not how it's supposed to work..It used to work fine before 2.8:
