I see this (and hear it from my American friends) from time to time. Is it just me who thinks it’s what Brits might call ‘arse-about-face’ (i.e. backwards)? Of course you could care less…Isn’t what you’re trying to say ‘I couldn’t care less’?
BTW, it’s not just Yanks - in the UK if something is unexpectedly good value, you’ll sometimes hear ’it’d be cheap at half the price’. !!! YES, IT WOULD!! Isn’t what we mean 'it’d be cheap at TWICE the price? Is there some cosmic thing I alone am not getting? Do I need to get out more?