This power flow "to device POS and returns on device NEG". Are you referencing Conventional Current flow or Electron current flow.
High school and Navy/military schools taught "conventional" to thousands, maybe millions. I was one of them. I later learned from college snobs that this was "hole theory" rather than actual electron flow. Doesn't effect much in the way of electrical equations, or the way things need to be connected in order to function. Chemistry, yes. But, the integrity of the current loop must be intact using either theory.
Perhaps I came along a little later. My High School instruction on this topic included some electrical history. Including the "convention" formed and adopted by the electrical inventors, scientists, and like of that time indicating "conventional current" flowed + to -. This was later proved incorrect soon there after but was retained to eliminate confusion (egos) at that time. My teacher was a retired International Harvester man. Who often queried to us "why do you think IH products are all Negative start". The old ammeter used on older vehicles can attest to the actual electron flow - to +. And yes in simple circuits the math is the same, the same consensuses were reached not to correct the original "convention".
Later on in formal instruction, withstanding the "snobs" did I learn of Hole Current. Even with my limited exposure to Hole current back then, it wasnt referred to as a theory. While hole current flow may still be debated, one rarely reads one on electron flow.
I snapped a screenshot of some current Honda OEM cbr500 rear turn signal lights
And what is the relevance of a "parts breakers" picture? It shows no connection or attachment method to frame, or pathway beck to battery terminals.
Many signals are rubber vibration isolated. This of course breaks the electrical path, requiring an augmentation to make it complete. For example, the CB550 grab bar connects directly to frame and the turn signal attaches to it. The signal socket galvanically attaches to an added bracket that surrounds the rubber, separating the path to the grab rail. The turn signal Green attaches to the bracket and then routes to bike harness green. Why do you suppose they added an extra bracket and wire for green path when the frame was so conveniently accessible? Answer: to avoid sending currents to/through frame or joints to the frame. Same is true for front turn sigs on models I have examined. I can't speak for all motorcycles or cars I haven't examined. But, I think I understand the pitfalls and benefits of electrical attachment methods. Galvanic corrosion is a real thing. There are many references and explanations on the interwebs.
Cheers,
That picture as is the one of the points should be self explanatory and testament to Spanner's and Scottly's post. My signal lights are wired the same as yours on my F1/2/3 also. And As pictured in the modern photo, they must rely on galvanic current (dc) flow through the bulb's base, socket, and bracket, all of which may be dissimilar metals. Which would still be exposed to your galvanic corrosion concerns regardless of the wire Honda provided. The point plate picture references the above posts indicating manufacturers have incorporated frame, engine, chassis, grounding circuits utilizing similar and dissimilar materials in their primary designs for some time and still do.
