[NeedMoreTea]

That makes sense for a 4 drawer, 5' tall filing cabinet -- which generally all have the interlock, and little to none for a 3 drawer under desk unit with drawers half the length or less of a filing cabinet. Even if you wanted to load them as heavily as a file cabinet, the drawers are generally far less substantial or well made. Doubly pointless considering the drawer unit shown has no filing drawer. Most of those solve the possible tip with a castor or slide under the front of the sole bottom filing drawer.

[jmull]

It just depends on what you load into the drawers. Since essentially the contents of only one drawer at a time is accessible in any case, it's the right UX decision.

Anyway, you need to close those drawers eventually, right? Why not before opening the next drawer?

Put another way, the alternative is to support the general use-case of disorganization: "I'm not sure where the thing I'm looking for is, but I need it in a hurry!" Do you really want to categorically assume in such situations that people have mitigated the tip-over risk in some external way? Just to allow for high-speed riffling?

Your castor idea only really helps if the search happened to start with the bottom drawer first. That's sorta logical, at least in some cases, but I don't think you can come anywhere close to assuming it's going to happen all the time.

[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.

[hinkley]

I have a three drawer underdesk cabinet with five wheels. The fifth being on the front of the file drawer. Don’t think that one is tipping over.