Yea, it’s a pole barn. And you’re right… nail plates were used to construct the trusses. Other than that, no nails. The builder even bragged that he could unbolt the whole barn and move it somewhere else.
At any rate, I now understand why nails are still used.
Aren’t nails used for temporary support when gluing and before screws are added?
OK how about ‘more subject to catastrophic failure’ 
Good Lord. NO.
Building codes at least here in Canada specify nails for most framing. Three 12d nails for example for fastening a 2x6 stud to the wall plate. Nailing schedules for sistering LVLs for a 2 ply 10" beam will specify 4 rows of 12d nails at 16" centers. You can do it with screws but a fussy inspector could fail you or demand an engineers letter. Standard 3" #8 construction screws do not have the shear strength of a 3 1/4" 12d framing nail.
As others have mentioned speed is a crucial issue. Framing crews do not have the time to fuck with screws. Nail guns are an order of magnitude faster than a 1/4" impact driver driving a screw. A carpenter is going to have screws in his pocket and an impact driver in the front seat because they are handy but there are whole framing crews without a single screw gun.
Thats not to say screws dont have their place. Subfloors are glued and screwed, but every framing crew shoots the subfloor down fast with nails and it gets screwed down later by another contractor using a Quickdrive with collated screws. Cabinets and hardware are installed with screws. Engineering details may specify screws to join a plates in a tall wall for example but they will be expensive Simpson or Other engineered fasteners. Base, casing and other trim is installed with 18 gauge air driven brads, 23 gauge pins for fine work and sometimes 15 or 16 gauge finish nails for headers or heavier elements. I use screws lots for quick repairs that are not structural. I like to install my door jambs with screws for the greater adjustability.
Screws have their place and modern impact driver improve their usability, but for structural framing air driven nails are superior.
Not building but… I used to run a shop where we packed machinery in large wooden crates and cases. when I took over in the 70s all the nails were driven in with hammers and I well remember a heated discussion about the best weight for the hammer.
Eventually we switched to air driven nail guns and these were much more secure because the nails were coated in resin. This melted by friction on entry and provided lubrication; then set to make the nail secure.
We also used a lot of pallets, and I well remember how hard it was to dismantle broken ones. This because they were constructed with nails that had a coarse thread which made it hard, even with a nail puller, to pull them out.
In what application?
Gluing is commonly used for furniture where vises are sufficient to hold while it dries and nailing holes in the pretty wood you’ve taken a lot of time to craft is contraindicated. I can’t see using nails as a temporary support.
I’m struggling to think of an application you would nail first just to screw later.
drywall might be held in place with nails and screwed to secure.
I suppose that’s possible but I really don’t see the advantage. With a good screw gun you can shoot a few screws into a sheet with one hand while you hold it with the other in just a few seconds. Hammering generally requires 2 hands making it even more unwieldy.
Well for what ever reason a lot of experienced crews do it this way. The sheets are tacked up with a few nails and the junior guy (or sometimes a different crew even) goes around with the gun and screws them later. Interior walls are often glued and may not even get screwed.
Some newer guns use collated screws so with these the point of nails seems even less. I assume that for some guys they are so used to nails and fast with them that there is not much advantage.
Ah, I see the problem. A #8 screw with a diameter listed as “.164 inch” is talking about the pitch diameter, i.e. the diameter at the middle of the threadform. This means the min diameter is thinner, which is why for a similar nominal diameter a screw has less shear strength. Got it.