It's not surprising that different individuals would focus on different things. But I'm curious how much of the subject matter comes from what they happen to know about and follow based on their broad interests, versus how much of the subject matter comes from seeking out any news items that they might be able to provide social commentary on. If you study an individual cartoonist's work for a long enough period, I'm sure you'd be able to figure that out, but it's interesting to look at instead a collection of work by different cartoonists from a specific period and see if you're able to suss out their motivations.
Also, I feel the need to provide a extra bit of kudos to Darrin Bell who, I think, has by far the most powerful statement in this collection of cartoons, and possibly the most powerful statement I've seen in editorial comics since... well, certainly since the Ferguson protests from August. Probably further back than that. I thought that even before I noticed the fist emblazened on the badge to give it added emphasis.