True for most of them, but check out the ones made by Lenox: http://www.lenoxsaw.com/utility.htm
They're 0.025 inch thick (heavy duty) bimetal blades; a thin, high speed steel edge welded to a spring steel back. Just like bimetal "shatterproof" hacksaw blades. These are also edge coated with titanium (TiN), and have four notches instead of two, so they can stick out further than regular blades. They claim that these last three times longer than regular utility blades. You can find them at Home Depot for about 40 cents/blade in 50 packs. I think the 5 pack was $2.50 or $3.00. Better to try them out that way, than sending for the free sample they're offering if you reply to their survey. They want too much info for my taste. See the free offer at the bottom of the http://www.lenoxsaw.com/index.html homepage. But it shows a good picture of them, as well as a crazy photo of one of them bent by two Vise Grips WAY further than I'd ever bend a regular utility knife blade. They've shown them used this way to flush cut with a utility knife. I hope they used safety goggles! I like them, but then I'm not a drywall contractor that abuses blades, so YMMV.