Why don't methods have reference equality?

I had a bug where I was relying on methods being equal to each other when using is. It turns out that's not the case:

>>> class What:
...     def meth(self):
...         pass

>>> What.meth is What.meth  # This is False in Python 2
True
>>> inst = What()
>>> inst.meth is inst.meth
False

Why is that the case? It works for regular functions:

>>> def func(): pass
>>> func is func
True

_{See also: How does Python's attribute lookup process work?.}