You really only need to know a few knots for camping and backpacking: Square, double half-hitch, taut-line, overhand, etc. The ones I use the most are the ones I remember. I keep a field manual with me for the ones I use rarely. The same with scouts - If they go camping frequently, they will get it through practice. If they are parlor scouts, they will forget.
Self-reliance in the outdoors is a major mark of a Scout and knowing knots are essential to that end.