When you start at a new job here in the U.S., the default means of payment is usually a paper check. Most folks will quickly set up direct deposit so that their employer deposits their paycheck directly into their personal bank account - the incentive to do so is that you receive your funds faster than if you deposit a paper check. Even if you set up direct deposit on your first day on the job, you may still receive your first paycheck as a paper check simply because the wheels of payroll processing turn slowly at some (large) companies.
A counter example is a self-employed contractor - perhaps a carpenter or house painter. These folks are paid by their customers, homeowners and such. Many larger, well established contracters now accept credit card payments from customers, but smaller independents may be reluctant to set up a credit card merchant account to accept payment by card because of all the fees that are associated with accepting credit card payments. 3% transaction fees and monthly service fees can be scary to any businessman who already has very thin profit margins. In such cases, these contractors prefer to be paid by check or in cash for the simple reason that there are no fees deducted from cash payments.
There are a few folks here who don't trust direct deposit, or more specifically, don't trust their employer to perform the deposit correctly and on time. Some feel uncomfortable giving their bank info to their employer, fearing someone at the company could steal money from their account. In my experience, the folks who prefer a paper paycheck are often the same folks who rush to the bank on payday to redeem their paychecks for cash. They may have a bank account (helps with check cashing) but they prefer to carry cash.
I operate in a manner similar to you - I use a debit card or credit card (I only have one of each) for nearly all transactions in daily life, I use electronic payments through my bank to pay my regular bills and mortgage, and I receive my paycheck by direct deposit. There have been periods where I haven't written or received paper checks for so long that I have to hunt for where I put my checkbook!
Even though I use a debit card for most store purchases, the bank account behind that debit card is actually a checking account according to the bank. Again, the system defaults to paper checks and you have the option of going electronic as well.
Before we judge anyone who doesn't use direct deposit or who prefers to be paid in cold hard cash, consider that direct deposit is a luxury of stability. Steady job, home, etc. Direct deposit doesn't make sense for a contractor or day laborer who expect to work for a different person each day or week.
I don't think this is all that unique to the US. There are people in every city and country who don't have long-term employment with a single employer and therefore prefer cash or paper check over electronic payments.
I'd be willing to bet that this applies to the majority of people on the planet, actually.