IIRC, no Prius batteries have been replaced due to age yet.
And the baby boomers all haven’t started collecting social security either, but it’s coming.
And the Prius’ bigger footprint to build than the Hummer. Not even out of the factory it starts off at a loss to a HUMMER!!! Think how far back it starts to a good fuel car like a Chevy Cobalt. Or even a regular Civic.
The batteries probably slowly degrade as opposed to outright failing. That would mean that the gas engine part of the hybrid ends up working a bit more. A driver might not notice the slow decline in efficiency for a while.