  The statement of the title is shown by numerical simulation of homogeneously
sheared packings of frictionless, nearly rigid beads in the quasistatic limit.
Results coincide for steady &#64258;ows at constant shear rate &#947; in the
limit of small &#947; and static approaches, in which packings are equilibrated
under growing deviator stresses. The internal friction angle &#981;, equal to
5.76 $\pm$ 0.22 degrees in simple shear, is independent on the average pressure
P in the rigid limit. It is shown to stem from the ability of stable
frictionless contact networks to form stress-induced anisotropic fabrics. No
enduring strain localization is observed. Dissipation at the macroscopic level
results from repeated network rearrangements, like the e&#64256;ective friction
of a frictionless slider on a bumpy surface. Solid fraction &#934; remains
equal to the random close packing value &#8771; 0.64 in slowly or statically
sheared systems. Fluctuations of stresses and volume are observed to regress in
the large system limit, and we conclude that the same friction law for simple
shear applies in the large psystem limit if normal stress or density is
externally controlled. De&#64257;ning the inertia number as I = &#947; m/(aP),
with m the grain mass and a its diameter, both internal friction
coe&#64259;cient $\mu$&#8727; = tan &#981; and volume 1/&#934; increase as
powers of I in the quasistatic limit of vanishing I, in which all mechanical
properties are determined by contact network geometry. The microstructure of
the sheared material is characterized with a suitable parametrization of the
fabric tensor and measurements of connectivity and coordination numbers
associated with contacts and near neighbors.
