I googled “Saqqara boxes” and didn’t find any images where one could really tell. Could you link to the images you’re referring to?

Example: https://www.ancient-code.com/wp-content/uploads/2016/12/saqq...

Perhaps I’m just a philistine but it’s not obvious to me from that super-low-res photo that the carvings are so bad that they can’t have been made by the same people as the box itself.

The lines are, visibly, not even straight. The surfaces of the boxes are ground to flatness we could not improve on today.

From that photo I would actually say that the box is not a perfectly flat cuboid. If you look at the bottom left of the picture it looks to me as though the "face" is actually not perfectly straight. If you looked at this from the side I would expect it to look more like this:

     --- 
       |
       |
      /   <--- 
     |

The arrow shows our vantage point.

This doesn't seem to be entirely straight across the entire face either (unlike my crude ASCII "drawing"). Almost like a huge ball 'dented' the stone.

There's also a huge flash and glare going on which doesn't help and probably overexposes the specks that you see are also present in other pictures (like you posted in the sibling thread).

Yes, some faces have what look like dents in or scoops out of them, probably from fractures in the mother stone, or from quarrying.

If you know that then why do you say the lines aren't straight? The ones that look as if they weren't straight seem to be perfectly straight but are following those dents and thus look like they aren't. Especially if your vantage point exacerbates that.

I am saying they are not straight even on the flat parts.

Maybe it's easier to grind the surfaces flat than to carve in small detailed images.

I see that you have not looked pictures of any other Egyptian artifacts.

I mean, looking at stuff like this: https://upload.wikimedia.org/wikipedia/commons/d/d8/Apis_Sar...

There's not much writing there, but I wouldn't call that crude.

Relative to the tech needed to produce the boxes, that is extremely crude. But your pic is far from the most crude seen.

That there is no uniformity is more evidence that they were tagged.