[jacquesm]

Those drawers can be used to hang folders and those can be very heavy and easily tip over the whole thing if you would slide out all of them at once.

[NeedMoreTea]

That would be a 12" deep file drawer, which either do have an interlock, or in a desk side with single file drawer the castor or slide underneath, as mentioned.

The one illustrated isn't deep enough for hanging files -- maybe the odd ream of A4, pens and pencils. Will need an awful lot of carefully placed paperclips and pencils to tip. Which is why you rarely see those locking each other out. If you use it for storing your collection of lead weights you bring it on yourself (the base of the drawer would probably fall through anyway)... :)

[Aardwolf]

Those folders are normally in the bottom drawer, so it could not tip over very far, the bottom drawer would hit the floor.

Even if there's a top drawer with folders, to open more than one drawer, a bottom one would be open anyway, with the same result.