Isn't that because of lack of knowledge of Lee Enfields by the US importers who, when they ship, them they have the bolts removed and shipped separately to the rifles, and then when they arrive the 'Saturday Boy' gets told 'take one of those bolts out of that box and put it in a rifle' without realising the importance of the correct bolt being fitted to the correct rifle..
Not as critical for a 22rf rifle, but potentially a serious issue in a 'full bore' 303.