Alan, if we re-phrase your last line into
"I don't think it is wildly inaccurate to suggest that we hear of these sort of outbreaks less frequently from Turkey (or Egypt, the Emirates etc) than we do from Somalia. There must be a reason for that."
then it takes religion out of the equation altogether, and we can focus on the other parameters.

I don't know the answer of course, but I am guessing that it lies in a multiplicity of parameters, though one might reasonably group them into the following, beginning with the individual "potential perpetrator" of such an act, and the various effects on him/her from:

a) The collection of interests,pressures or causes leading one to rage (examples: insulting one's family, one's belief in a system to live by, threat to personal well-being etc)
b) The collection of inhibitors instilled into one by parental (and other) teaching, societal impact on an individual's beliefs, education, fear of repercussion etc
c) The individual's beliefs regarding the sanctity of life, both one's own and everyone else's; by extension also the individual's belief in various human rights.
d) The individual's thresholds within which the above three operate.
e) The impact on all of the above by mob mentality.

Looking at the list above, it's one hell of a recipe to get right - and many ways to get it wrong.