I deal with screws all day... and it's not just the customers.
I work in a hardware store and seen, almost, every screw out there. With most of them I can just look at it for a split second and tell you what it is, even down to the thread pitch. Metric and standard. I'm sure I'm not the only one that can do this, there's plenty of machinist out there in the world.
But, it always seems to impress the normal, run of the mill customer. They haven't even given me the screw from there fingers and I'm practically running off to get a replacement or the nut for it.
But, back to the subject...
Just today I was looking for a screw for a customer and he was hemmin' and hawin' about the old slotted head screws, that they're an obsolete product. I have to agree, in most cases. Except when machining other slotted heads on a nice piece of furniture.
I've also notice that the Hillman Fastener Co. (our supplier for most of our stuff) is switching there assorted bins over to more and more phillips.
Just my 2 cents.