The problem, IMO, is that people rely too much on hyper-reacting to instances of bullying once they get out of hand instead of setting meaningful expectations for appropriate behavior on the first day of kindergarten (and continuing thereafter). A little compassion and and a little courtesy go a long way in pre-empting the problem to begin with.

I completely agree. I'm often surprised at how other parents let their children treat their siblings- let alone strangers! We don't let our kids be mean to one another and for the most part, they're not. When friends make comments like, "well, you know how brothers and sisters are..." I tend to respond, "well, no, I don't." A little joking is okay, but being mean is NOT.
And there ARE simple rules that teachers can implement. For example, in ds10's school, you are not allowed to refuse if someone asks to be your partner, unless you already have a partner -in which case you say, "sorry, I am already partnering with X. If you can't find someone, we can ask 'teacher X' if three people can be in our group," or something similar. I was worried about how ds10 would do in the 5th grade math class because there are a bunch of kids who are very clique-y in there and they often partner up for things. However, I'm in there every week and I've found it's never really a problem. Since he's not a 5th grader and knows fewer kids, he often is the one asking instead of being asked, but he's never refused and he is asked about 30% of the time. That's just one example - not being able to pick seats at lunch is another, not being able to pick teams in PE class, pairing up kids in a "lunch buddies" small group... It's definitely not perfect where I live, but at least they're trying.
We were lucky. Ds11 isn't the least bit sporty (think orchestra/math club/chess) and he's fairly quiet, but he's also in the 95th%-ile for height. DH was taller than his 4th grade teacher (reached his full height of 6'3" in middle school) so even though he was equally nerdy, lol, he was never bullied. Ds10 is smaller, but he's sporty and talkative and friendly - really great emotional IQ. Thank goodness it wasn't the other way around!
The girls weren't bullied, but honestly, that has a lot to do with looks. It's sad to say that being very attractive goes a long way for girls.