I wouldn't say it's secure. Anything I've paid with an electronic bank draft just needed my routing number and account number without any sort of verification, so with a copy of my paper check (like the cashier or whoever else handles them) someone could easily use my information for nefarious purposes. As soon as that check leaves your hand, your account information is out in the ether.
Sure. But the same information is encoded on your debit card. So anyone with physical access to either a check or a debit card can access your account. Hence, needing to trust the people you do business with. The difference is that the data on the card can be picked up electronically. There are a host of methods, some of them very hard to detect, to read that data without having to steal the card itself. While I suppose someone could set up a hidden camera near a POS to read the routing numbers off checks being used, I've never heard of anyone actually doing this.
People generally do check fraud by creating accounts with bogus names and then passing the checks and taking advantage of the delay in fund withdrawal to maximize the amount they can steal. This is why the banks prefer folks using cards. But the checks are actually far less likely to result in *your* money being taken from you. Hence why I mentioned the issue of security.
Crazily enough, my name and address are also on my checks, and you'd better believe that vendors keep that on file. Plus, what's stopping the bank from using that transaction information from your check? Banks are the ones who issue credit cards, you know.
It something which can be done, but is less likely to. In order for your bank to know what you purchased with your check, the vendor has to have some extra system set up to do this. Most vendors treat checks like cash purchases. They get the authorization to accept the check, put the check in the drawer (just like cash) and then drop it at their bank when they make their next deposit. The bank handles the details on the back end, but there's no innate way for the bank to know what was purchased with any given check.
Obviously, the vendor *can* implement a system which correlates checks to specific items purchased, but that's not an innate feature of using the check. Many vendors attempt to collect name, phone number, etc when you buy something from them no matter what method you use. Having a check with that information on it just lets them easily do this. But credit or debit purchases actually include the receipt with the financial information. That information is then available to both sides of the transaction and you kinda don't have a choice about it.
It's not about absolutes, but degrees. You're also missing that most credit/debit transactions should be replaced with cash, not a check. Checks are for occasional largish purchases either from specific vendors, or usually for paying bills of some sort. You don't buy a bag of chips and a soda with a check. You pay cash *or* use a credit/debit card. That's the most common comparison and IMO cash is much easier to use, much more secure, and absolutely more private.
Oh. And silly commercials aside, it's faster.