Originally Posted by squeakywheel
Probably because there is no dish in a front wheel. I don't expect to ever break a spoke on my SS MTB rear wheel. The hub takes up most of the 135mm space and the spokes aren't dished at all.
Edit: Oh, and I don't really ride it off road much. For my use, it's pretty much indestructible as long as I keep rigid objects from finding their way in the spokes while riding.
I think the lack of dish is only part of the reason. The other part is that the front wheel is rather static. If it were subjected to the lopsided torque that the rear wheel sees, you'd probably break spokes on the front wheel too. I wonder if we had drives on both sides of the rear wheel, if spoke breakage would be a thing of the past.