If you see someone with a quiver you can simply walk up to them and reach towards the lower half of the quiver and pull arrows out of it. Tested this on an afk fellow and you can take all their arrows (I put them back).
Yeah, this seems to be the only “benefit” to having a quiver over simply having a bag of arrows, and not much of a benefit at that! I was hoping quivers would allow carrying multiple arrow types together, but instead they just make our laboriously crafted arrows less secure…? hey ho -_-