12 V is not enough to pass through unbroken skin, yes. But 12V has plenty to pass through some bolts and heat up enough to burn your house down.
You may be interested in StyroPyro’s video where he wired 100 car batteries in parallel. Still 12V, but huge current capacity.
You get charged a 3% transaction fee for using a credit card, which more than wipes out the value of any points you might earn.
Tap for spoiler
(Excluding the Bilt card, which used to let you earn 1% on rent and they processed it like an ACH/bank debit, so no credit card fee. But they recently restructured their rewards and it’s not nearly as easy to profit now.)