prepare_cached() unused in selectall_arrayref() et al

Why do the higher-level DBI methods such as selectall_arrayref() internally use prepare() rather than prepare_cached()? or at least why is there no option to enable that? It seems that the only way to utilize DBI's internal statement handling caching is to directly call prepare_cached(), but managing that is not as convenient or transparent as just using the higher-level methods such as selectall_arrayref().

--davidm
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