As a string player, I would hardly say that it's the difficulty of the instruments. In fact, I wouldn't say that they're much removed from brass or percussion. It's just more obvious with string instruments (in tone and intonation) when you're faking it.
That said, I do think that it requires more discipline than most other instruments to derive a pleasing sound from a stringed instrument, given it's lack of auto-tuning mechanisms, such as valves on a brass instrument or keys on a sax or flute. Obviously kids from a very early age understand how to hit things with sticks, but these, too, require a certain finesse.
It's not so much anything for or against the kids in either group as it is to divide the ones who are in it because their parents are forcing them and likely don't care or don't practice from the ones who are out to advance on their instruments. This is why most schools divide the bands into Concert band (the lowest level), Symphonic Band (intermediate), and Wind Symphony (the highest level). It can become much more obvious and much more painful for both those listening and participating, when a child is not with his peers in skill level in a string program.
I'm glad that people are curious about these things. Seeing people who are curious as to how and why things work and who are willing to ask questions to find out puts a smile on my face. If you have any further questions, feel free to ask, and if I don't know the answer, I'll try and find someone who does.
P.S. I play the double bass, in case you'd like to know. =)
Edited by ShackMan (07/09/09 07:49 PM)
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Music Gear Review - Keyboard/MIDI and Songwriting Editor/Mod
"I don't like it, and I'm sorry I ever had anything to do with it." - Erwin Schrodinger, on Quantum Physics
Keys: Nord Stage 88, Nord Lead 2, Yamaha W7
Upton Bass Custom Upright, BSX Allegro EUB, '80s Peavey T-40, MIM Active Jazz Bass, Godin BG-5, Fender Bassman 100, `68 Fender Bassman 50 head, Gallien-Krueger Fusion 550, SWR (pre-Fender) Goliath III 4x10, Markbass 2x10 Traveler