David, I honestly am confused by your first and last post. When framers speak of shear planes, we are concerned with the supporting grain beyond the joint, aka relish. When joints apply force close to and towards the beams end and when tenons are expected to be in tension, then end distance and relish become a matter of concern. So with a strut close to the end, we take tenon depth times end distance times NDS Fv value times 2 equals the force the joint can safely resolve. We multiply by 2 because there will be two shear planes of equal area. For pegs we take center line of peg to end distance times tenon thickness times Fv times number of pegs times 2 [two shear planes per peg} equals force limit. In the case of your strut to beam joint, you have ample end distance.

In the case of the French manual, the drawing seems to me to be of a major rafter landing with a scant tenon with a nailed cleat supporting the load, not applicable to your case.