This has never been on my list of worries. I deal with giving my credit card information to low-paid clerks all the time. My personal information is available to a tremendous number of data center customer service reps. And there’s no such thing as privacy anymore, in any case.
The real key is how you deal with situations — checking your own financial information on a regular basis, disputing inaccurate charges, etc.
But the hotel key card thing, it just isn’t so.