again, "most" people.. any stats to back that up?
most will have a USB-A power plug, but not necessasrily the cable, as the iphone ships with a USB-C cable.
by "most" you are actually meaning people upgrading from an older iphone model.
you are excluding everyone that is upgrading to an iphone from another mobile device. those are most likely to have a power plug with a USB-A port, meaning the cable shipped with the iphone is useless. they either need to purchase a different cable or a different power plug.