We had some other pictures posted in the general forum. The back-stab design is completely sound and actually has very good surface area! The key is that the wire must be STRAIGHT and installed properly. If the wire is kinked or too short or otherwise poorly installed then, yeah, you're going to have a fire risk. Why not post pictures of screw terminals that have been put on backwards or with too loose or a loop, or too short so the insulation is trapped and a poor connection made?
https://www.electrical-contractor.net/ubb/Forum1/HTML/007963.html

Steve Fehr:
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The infamous back-stab revealed! This is (was) a Leviton 15A 120V light-duty light switch.

[Linked Image from img100.imageshack.us]

Honestly, there's a surprising amount of contact area in there- there is a dimple sized for #14, and a large spring to hold it in place. The wire would have to be as straight as possible, though, or else it might only contact at 1 or 2 points instead of along the length. But installed properly, 3/8" of the wire will have contact along about 180° of circumference.

Edit: it's stamped MADE IN USA, btw

Theelectrickid:
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I have five pictures of a Slater Spec Grade (circa 1973) that was fully stabbed, disassembled. They start here: https://s29.photobucket.com/albums/c266/Macsignals/Electrical%20Stuff/?action=v iew¤t=100_4093.jpg

I'll have to hit one with a hammer and see if I get different results. [Linked Image]

Ian A.

[This message has been edited by SteveFehr (edited 03-04-2007).]