Effort Controller at each joint... under the hood?

[Giggus]

In lbr_ctrl.launch you can see:

    <!-- Spawn controllers - it uses an Effort Controller for each joint -->
    <group ns="$(arg robot_name)" unless="$(arg trajectory)">
        
        <include file="$(find lbr_control)/launch/lbr_control.launch">
            <arg name="hardware_interface" value="$(arg hardware_interface)" />
            <arg name="controllers" value="joint_state_controller
                 $(arg hardware_interface)_A1_controller
                 $(arg hardware_interface)_A2_controller
                 $(arg hardware_interface)_A3_controller
                 $(arg hardware_interface)_A4_controller
                 $(arg hardware_interface)_A5_controller
                 $(arg hardware_interface)_A6_controller
                 $(arg hardware_interface)_A7_controller"/>
            <arg name="robot_name" value="$(arg robot_name)" />
            <arg name="model" value="$(arg model)" />
        </include>
    </group>

I do not understand why this should be an Effort Controller as written in the comment.
If you look at the config file (lbr_ctrl.yaml) you can see defined position and velocity controllers.

Effort controller does simply mean that there is a PID control in position or velocity that then send torques commands to the low-level controllers? Why also PID are not defined in position control?

Cheers!