What I find strange, (and nobody has been able to answer this for me), is that on a plane blade or a hand chisel you have two edges, i.e. a bevel, at the cutting edge to help prevent wear/blunting, but you don't on turning tools.
Then allow me to answer that for you...
Bench plane irons get a lot of use, and require frequent resharpening. This was especially the case in the days before machine planing (early to mid 19th Century) when every square inch of floorboard surface, panelling, etc had to be planed by hand. All they had to do this were big wooden planes with thick, tapered irons. If you've ever ground the full bevel of a 2in/50mm chisel by hand to get the nicks out you will know exactly how much work this is on a thick tool. Now imagine that you are a bench joiner back in the 1780s charged with planing hundreds of feet of oak decking for the Royal Naval Dockyards every day, by hand (there are now power tools back then). Oak being oak it will blunt your plane iron mayve every 15 to 20 minutes in the course of the day. If you don't sharpen your plane iron regularly when it starts to blunt you will soon reach the point where you simply aren't strong enough to push the plane along the oak at all. But if you stop to hand sharpen the iron it you will loose 5 to 10 minutes of your paid work time (because you are on price work). The solution is to sharpen at a main angle, say 30°, then put a micro bevel on the iron at 5° less, or 35°. That micro bevel is only a millimetre or so wide, but the cutting edge whilst slightly blunter actually has a stronger edge (so will keep it's edge longer), and leaves the blade in the main part to behave as though it is a 30° bevel throughout. In addition honing that micro bevel takes only seconds, so you can hone the blade up to maybe a dozen times before needing to do a full regrind because the micro bevel is now 4 or more millimetres wide. That will save you maybe an hour's effort every day.
They found that the same principle could also be applied to bench chisels, which also tend to be the workhorses and get resharpened regularly.
But you won't see the same approach on moulding plane irons (because life is too short and you also risk deforming the shape of the iron - the ruddy things are often difficult enough to sharpen well with a single bevel), the same goes for gouges and carving tools, and you don't see them on mortise chisels which are already much blunter than bench chsiels and which often aren't used so intensively.
Turning tools are somewhat like carving tools in that they are often awkward to apply a secondary bevel to without messing up the cutting edge profile (think roughing gouges). Combine that with the frequent need for resharpening, and a secondary bevel quickly becomes an unaffordable luxury which delivers very few, if any, advantages to the turner in most cases.
