I have just tried as you suggested, with vertical lines, and the situation is much worse than you describe it.
Two shape layers, a vertical line on each, a little ways apart.
Using the V tool, if neither layer is selected (there are no other layers in this project) then it's impossible to select either layer with the V tool, except by stumbling over the hidden mid point of the layer.
Even a marquee drag selection over the line won't select it. That's odd, in the extreme.
With no layer selected, the pen tool also doesn't work.
That's not just a matter of mixed metaphors about tool and screwdrivers (sorry, Rick) that's just plain broken UI.