The government expires your driver's license because they want to charge you for a renewal. You can tell that this is the only reason because it's the only thing they want in order to give you a new one. They do nothing to confirm that you still know how to drive.
But Let's Encrypt doesn't charge anything. All they want is to confirm that you still control the domain. So why doesn't "the DNS record they had you add to begin with is still there" satisfy that requirement and allow you to repeatedly renew the certificate until it stops being there?
Tie the DNS challenge to the public key in the certificate. Then as long as it hasn't changed you can update the certificate without giving the update process modify access to the DNS server.
But Let's Encrypt doesn't charge anything. All they want is to confirm that you still control the domain. So why doesn't "the DNS record they had you add to begin with is still there" satisfy that requirement and allow you to repeatedly renew the certificate until it stops being there?
Tie the DNS challenge to the public key in the certificate. Then as long as it hasn't changed you can update the certificate without giving the update process modify access to the DNS server.