What, pray, happens if you send in your check payment and
Walmart credits the check to your account normally and prepares their bank deposit and, somewhere along the line from Walmart to their bank to the Federal Reserve to your bank the check got lost?
Maybe an armored truck got hijacked or crashed and your check (along with thousands of others) got lost.
Maybe a piece of luggage with a deposit bag containing your check got lost by an airline.
So your bank doesn't get back the check to clear, and deduct the payment from your account with. They with so many other checks coming in and going out for you and their other customers might never notice the absence of this one check of yours.
I was a little slow to adapt to electronic payments but eventually I cut down on writing checks and now do most of my transactions over the phone or on the internet. But I still deal with a few companies that charge a fee for everything, everything other than checks sent in the mail or payments made in person in their offices.