Tolerance you’re referencing relates to the distance of one side to another, not the shape of the corners; the dice you linked to have their corners rounded (aka shaved) if you look at the image.
If casinos actually did use dice that were extremely cubic, the dice would be cutting patrons' fingers and wrecking the felted surface of the craps table.
I can't find measurements for the radius of curvature on razor dice edges, but I'd be surprised if they're truly as sharp as claimed. Without even considering the liability aspect, it seems inconvenient for a casino to pause the game because someone is bleeding on the table or dice.
I also wasn't able to learn how often the felt of a craps table is changed, though I came across something that said the felt's useful lifetime is prolonged by a foam rubber underlayer.