  The incidence of giant arcs due to strong-lensing clusters of galaxies is
known to be discrepant with current theoretical expectations. This result
derives from a comparison of several cluster samples to predictions in the
framework of the currently favored $\Lambda$CDM cosmology, and one possible
explanation for the discrepancy is that this cosmological model is not correct.
In this paper we discuss the incidence of giant arcs in the Red-Sequence
Cluster Survey (RCS), which again shows significant disagreement with
theoretical predictions. We briefly describe a total of eight strong lens
systems, seven of which are discussed here for the first time. Based on the
details of these systems, in particular on the ratio of single to multiple arc
systems, we argue that it may be possible to explain this discrepancy in the
currently favored cosmology, by modifying the details of the lenses themselves.
Specifically, the high incidence of multiple arc systems and their overall high
redshift suggests that a sub-population of the global cluster population is
responsible for much of the observed lensing. The lack of lensing clusters at
$z<0.64$ in the RCS indicates that a property associated with clusters at early
times results in the boosted lensing cross sections; likely a combination of
ellipticity and elongation along the line of sight, substructure, and changes
in the cluster mass profiles is responsible. Cluster mass, which should evolve
to globally higher values toward lower redshifts, is clearly not the most
significant consideration for the formation of giant arcs.
