This is all interesting discussion about accuracy of the camera but I have a slightly different take on it.
I simply don’t want the camera to claim sub-1/4" accuracy.
[Some speculation follows, but I feel pretty good about it]
Aside from the economic argument against it, anything that accurate will require a lot of work to maintain both on the GF side and on ours as end users. I think the “click and go” aspect of Glowforge is its strongest asset, and we’d lose a good bit of that if we chase down tighter placement accuracies that have diminishing returns (see economic argument above, and that’s only about the user’s economics, not the equation on GF’s side). I don’t want to get my camera to pixel accuracy only to have it go out of whack because humidity changes caused my table to shift somewhat, and causes some torsion in my GF frame, thus negating all that perfect accuracy. I don’t want to put in a material piece that I didn’t even notice was very slightly warped, throwing off my accuracy to the point where I ruin a cut.
“…but these things don’t happen that often!” I can hear people saying. Not to you, but multiply that across all the people who use the GF in all the ways. People who keep the GF on a rolling cart. People who installed it in a non-climate-controlled garage. People who haven’t cleaned their lid camera lenses lately. People who installed a GF on a non-level surface. People who store their materials vertically vs horizontally. People who live in Minnesota and people who live in Puerto Rico and people who live in Austria, climate zones that are completely different from each other.
There are just a tremendous number of variables in terms of physical installation; variables that don’t move the needle enough to upset the 1/4" limit, but will likely throw off predictions in the sub-mm range. It’s a daunting task to do what you’re calling for in anything but a highly controlled environment. I just don’t see the benefits outweighing the costs to try to account for all that.
From GF’s more practical persective, if they claimed more than 1/4" accuracy it would no doubt lead to a sharp uptick in support calls. We already see enough “my alignment is off” posts as it is, that would skyrocket. I think the worst case would be for GF to roll out a system that is highly susceptible to environmental changes like this, giving us false expectations is absolutely worse than giving us a reasonable margin of error.
Essentially, having a reasonable and true expectation is what I think is important here. If you need higher accuracy of placement (anything less than 1/4" officially, probably less in most machines), I say optimize your workflow for jigs. You’ll save time, effort, materials, and frustration if you do.
[As an aside, and not to get too far off track, that’s where I think GF should be investing its development efforts: give us a dang pause action so jigging gets simpler and faster. They’re killing me over here.]