Not all uses cases for a car are the same. Some are held entirely on private property and are used as work vehicles where the seat belt chime would be unnecessary and distracting. Which is why most manufacturers provide a sneaky mechanism to disable it. I own the vehicle, why wouldn't they let me disable the nag?

Their solution? Make it intentionally complicated, but still possible:

Step 1: Turn your headlight switch off

Step 2: Unbuckle your seatbelt and turn the key to the off position

Step 3: Turn your key to the on position till the seatbelt warning light turns off

Step 4: Buckle and unbuckle the seatbelt three times and end on the unbuckled position

Step 5: Turn your headlight switch on for three seconds and then turn it off

Step 6: Repeat step number 3

Step 7: Wait for the seat belt warning light to turn on and off again then buckle and buckle the seat belt