I didn’t open the photo on first read so my mental image of the situation was a bit off (I missed that it was on a shower door, and pictured it perched on something like the rim of a bath)
But my guess before reading the answer was “there’s some source of resistance that the added weight helps it to push past” (competing with “there’s some small amount of off-centre shampoo in the bottom of the bottle”—although that should have been excluded by rotating it, but maybe it somehow keeps moving?). So I guess I was under-specific but not wrong.
I didn’t open the photo on first read so my mental image of the situation was a bit off (I missed that it was on a shower door, and pictured it perched on something like the rim of a bath)
But my guess before reading the answer was “there’s some source of resistance that the added weight helps it to push past” (competing with “there’s some small amount of off-centre shampoo in the bottom of the bottle”—although that should have been excluded by rotating it, but maybe it somehow keeps moving?). So I guess I was under-specific but not wrong.