Column: The one day all year when companies think they can creepily invade your privacy

So, it was recently my birthday. No, I’m not going to tell you here what day it is or how old I am.

My determination to keep these tiny nuggets of personal information to myself is unavailing, anyway, because some big corporations that I have even casual business relationships with know them. And they’re not shy about letting me know that they know.

I know this because they’ve been wishing me Happy Birthday.

During the week leading up to the big day, and especially on my birthday itself, I received nearly a dozen computer-generated birthday greetings. Among the well-wishers were my mortgage lender, a car rental company, and Google, whose search page welcomed me with a special doodle featuring birthday cakes and candles. The words “Happy Birthday Michael� appeared by magic when my mouse pointer hovered over the drawing.

I’ve always found these robotic good wishes inordinately creepy. Some companies are more on the ball about my birthday than members of my family, but that doesn’t mean the sentiments are particularly heartfelt.

They’re mere artifacts of corporate marketing. Google’s PR staff isn’t going to be any more cooperative on my birthday than on any other day if I ask them for a comment about a touchy subject. My mortgage lender isn’t going to look more kindly on a request for a free month because I asked on my birthday, even though they emailed me to say, “We know it’s your special day!� (Special how?) One exception: Best Buy, which sent me a $5 birthday gift certificate. Now, they care.

These birthday eCards merely hint just how much of our personal information gets snarfed up by the businesses we engage with routinely. And the fact that businesses feel no compunction about telling us they know what day we were born, and presumably our age, points to how willingly we provide them with what used to be considered personal data.

After all, with few exceptions my corporate well-wishers didn’t have to search very deeply for my birthday. The financial institutions got it in the course of my opening a bank account or applying for credit, since it’s needed to search my credit history. The supermarket chain where I do my grocery shopping and a certain major airline I frequently fly got it when I joined their customer-loyalty programs. Google has it because I opened a Google account to use Gmail, and linked it to my Chrome browser. Facebook hasn’t sent me a birthday eCard, but since I get regular notifications of my “friends’� birthdays, I assume all my “friends� now know mine.

Think about how much more these businesses may know about us. A supermarket chain knows the brand of cereal you buy, how much red meat you consume, whether you’re a drinker. Most know your address and age, which helps them slot you into socioeconomic and demographic categories.

As ProPublica reported last year, data-mining services “collect lists of people experiencing ‘life-event triggers’ like getting married, buying a home, sending a kid to college—or even getting divorced.� Experian sells clients “names of expectant parents and families with newborns.� Google can tell which websites you’ve been visiting.

Many firms that collect your personal data publish privacy policies aimed at giving you confidence that they’re not peddling your life, from your Social Security number on down to your shoe size, to anyone else. But these policies are often porous. When RadioShack went bankrupt, for instance, much of the data it had collected as a seller of mobile phones and services for Verizon, AT&T, and Sprint--including 8.5 million email addresses, 67 million customer names and mailing addresses--was put up for sale. A so-called privacy advocate the bankruptcy judge appointed to advise on the sale said that most of the data were “available from public sources,� so customers shouldn’t worry.

But that’s wrong. We all should worry about how much strangers know about us, how they use it, and especially how they safeguard it. (They don’t safeguard it, as customers of Target, JPMorgan Chase, and Anthem know all too well.) The companies that have our data are so convinced we don’t worry that they’re getting smug about it. So my message to them is, thanks for reminding me, and leaving me with this little birthday shudder. Now wipe your databases clean.

Keep up to date with the Economy Hub. Follow @hiltzikm on Twitter, see our Facebook page, or email [email protected].

MORE FROM MICHAEL HILTZIK

Groupon, once a high-flier, lives down to investors’ expectations

Yes, Social Security is unfair, especially to women. But can it be fixed?

Yahoo’s Marissa Mayer utters the six scariest words about Silicon Valley