Back in 2013, there was not industry standard. Everyone had their own spec. One manufacturer stated the camera can withstand 100lbs of force...
Now there is an international standard using the IK code, such as IK10, which has a specific amount of force the camera has to withstand and still be functional and not have a broken dome, etc.
In addition, you can then easily compare that against an IK08 camera.
Typically these cameras also use "tamper proof" screws, but that is up for debate how tamper proof they are, and if they should have the pin in the middle...
There are IK ratings that define what level of impact the device can withstand, which are often used to define vandal resistance in terms of someone throwing a rock or swinging a bat at a camera.
And of course at this point, most people are familiar with IP ratings that define resistance to objects (from fingers to dust) that can fit through various openings, as well as water resistance.
IK10 vandal resistance and IP66 weather ratings are the most common, but I have not yet seen any manufacturers that go out of their way to show how the two correlate. Meaning if your camera is IK10 and IP66 rated, does that mean it will maintain its IP66 rating after withstanding an IK10-level attack? Or, will it end up with seals being compromised, but otherwise functional, meaning the first rainstorm after a heavy rock impact will disable the camera.
So, while there are specifications that let you provide some meat to a claim of "vandal resistant", like most things on a spec sheet you cannot just take these at face value and assume that a given value means the product will actually perform as expected once you stack a few variables together.
So it's still somewhat ambiguous, as suspected.