Same reason you still use miles and pounds and degrees Fahrenheit in your measurement system: inertia.

Because cash doesn't leave a paper trail and not everyone can accept cards.

And third point necessary here: because U.S. banks don't have any other reasonable inter-bank transfer system.

Well, it does, but they've chosen to monetize it. I can transfer money to anyone with an account, but I have to pay $25 if I want it done today and $3 if I want it done some time next week.

I'd like to know that too. Never seen one in my life in Germany.

It's still an easy way to transfer money between two people, especially if your bank does mobile deposits through a smartphone. At that point, the check is really just a paper record of a transaction you intend to make with the bank account information prefilled for you. You don't have to worry about banks or devices utilizing different technologies, it just works...for the most part.

Because they work very well for certain types of payments.

Think about why this story is so noteworthy: because this sort of thing happens so rarely. The vast, vast majority of checks are written, sent, and cleared without fraud or incident.