Rails is driving me mad, part 2

In django/python, in development, whenever I change any source file it's automagically reloaded.

In RoR, this is true for some source files, but notably not the source files in my lib directory.

There's a way to fix that:
http://stackoverflow.com/questions/2129458/automatically-reload-rails-module/2138935#2138935

But why is this in an obscure SO question/answer, and why doesnt Rails automagically do the right thing?  And why does Rails permit you to do it wrong, for example by using require instead of require_dependency?