there are many designs with bicycle calipers. lower cost mechanical calipers tend to have one side that levers the pad into the rotor while the other pad sits stationary. Both pads often use a magnetic attraction to keep the pads from free floating & there's a spring steel clip that acts as additional help that binds the pads away from the rotor. For the one sided lever actuated pad design, the opposing pad may require a slight adjustment every so often to keep the rotor deflection at a minimum during braking.
The double pull lever is what makes adjustments a thing of the past, same goes for hydraulic designs.