Really? I have a collection of dozens and every one has clearance on those cutting edges.
Just two examples, first a 0.4000", factory sharpened:
The clearance is mostly radial, not along the length of the reamer. But it IS THERE. Those are cutting edges.
Another, smaller one (0.1868"):
Again, the clearance is mostly radial and it is a bit harder to see here due to the smaller size. But, again those are cutting edges. Just like drill's cutting edges.
If you look at these two reamers or most of the others in my collection from the side you will not easily see any clearance. It is a radial clearance and that is not like a drill bit. But it is real clearance and those edges can bite and cut into the material surrounding the hole.
Taper reamers, as sold in hardware stores, with a range from 1/8" to 1/2" and that are intended to enlarge holes in sheet metal, are intended to cut on the outer edges of the flutes. But machine reamers, like these, which are intended to cut a hole to an exact size will have the exact same diameter all the way down to the tip. They are intended to cut on these 45 degree edges.
Oh, BTW if you look close at the first photo, you can see the same lands that drill bits have on the outer edges of the flutes. These lands are there to prevent any cutting action there. They really are intended to cut ONLY on those small, 45 degree edges at the nose. They probably exist on the smaller one also but are harder to see. OK, I just checked with my pocket magnifier and yes, they are there on the small one too.
Ever measure the heel clear on that 45 leadin on the nose?
May look like it but these are not drill tips.
Bob