Noticing this myself. I've got
some translucency in the Finder sidebar and the Dock and Menu Bar are translucent but none at all in any toolbars. Apple's own description says (bold text is my highlighting):
Apple on their OS X page said:
Translucency
The translucent sidebar in your active window hints at whats behind it, giving you helpful context for where your apps are. Toolbars also have a touch of translucency, so you get a glimpse of the content behind them
but like you I don't seem have much of it. Not a biggie but puzzling. I suppose it depends what they mean by "a touch of" maybe? I've had my nose right up against the screen and I can't see a touch of anything in the toolbars.