It can and does happen. Recently, I bought a Jack Howard Classic, one of the last bows still in Jack's shop. It was brand new and as far as was known, unshot because no string could be found anywhere in the shop. When I received it there was no string. Since receiving it and a string from Charlie I did string it up, drew it back a couple times but never let go of the string-never been shot. Unstrung it and put it back in case where it was until it was sent to the new owner.
Granted this is a special circumstance being such a collectors bow but it can happen. Most of the time any bow has been shot at least a few times, or more.