Why won't the car doors lock, fellow car enthusiasts? When sitting inside and locking the doors, they can still be opened. What's going on?

Mechanical failure: The mechanical components of the car door lock, such as the lock cylinder, lock rod, or lock block, may wear out, rust, or get stuck, which could prevent the door from locking. In this case, you need to remove the interior panel to inspect and repair or replace the damaged mechanical parts.