The difference is that 1000kg of lead costs ~US$2000, and lasts forever, but 1000kg of lead-acid batteries costs ~US$9000, but only lasts for 10 years.
The mechanical equipment and supporting plant equipment to turn that 1000kg of lead into a power storage system is not free, does not last forever, and experiences mechanical wear and tear - in fact it likely needs constant maintenance on a cycle of weeks to months.
Whereas those Lead-Acid batteries will do their thing for 10 years, then can be recycled into new Lead-Acid batteries and do it again. The support equipment is all solid-state electronics (though still about a 20 year reasonable lifespan).
