The lock point is concealed behind the bib and can be revealed by clicking on any of the sensing zones. Feel free to adjust their size and shape to your liking.
Version 9 Added a special configuration notecard to the Hired Help uniforms that allows to set the uniform pockets as “sewn shut” roleplay wise. What this does in more practical terms is block access to the inventory as soon as the uniform is locked. (only if RLV is active obviously)
TO enable/disable this feature, all you have to do is to rename the notecard that can be found inside the Hired Help uniform root:
While the dress is a fitted mesh, it is not the case of the sensing zone prims or the padlock. Because every avatar is different, the shape of your avatar's torso will determinate where the locking post will be. Adjusting the position of the padlock is easy if you have a little bit of experience adjusting attachments: