Scale.

The average individual could not hold private gladiatorial contests, on a whim, at negligible cost. Killing a few innocents by torture, as public spectacle, is significantly less than repeatedly torturing large groups, as private entertainment, for as little as the average individual would have paid for their ticket to the cockfight.

Also, some people reckon the suffering of animals doesn't matter. They're wrong, but they wouldn't care about most of your examples (or at least they would claim it's because they increase the risk you'll do the same to humans, which is a whole different kettle of fish.)

Not to mention the sizeable fraction of car drives who will swerve in order to hit turtles. What the hell is wrong with my species?

Why do you always have to ask subtly hard questions? I can just see see your smug face, smiling that smug smile of yours with that slight tilt of the head as we squirm trying to rationalize something up quick.

Here's my crack at it: They don't have what we currently think is the requisite code structure to "feel" in a meaningful way, but of course we are too confused to articulate the reasons much further.

How do you know that they don't?

Well, I can't speak for the latest games, but I've personally read (some of) the core AI code for the toons in the first game of the series, and there was nothing in there that made a model of said code or attempted any form of what I'd even call "reasoning" throughout. No consciousness or meta-awareness.

By being simulated by the code simulating the game in which they "are", they could to some extent be said to be "aware" of certain values like their hunger level, if you really want to stretch wide the concept of "awareness". However, there seems to be no consciousness anywhere to be 'aware' (in the anthropomorphized sense) of this.

Since my priors are such that I consider it extremely unlikely that consciousness can exist without self-modeling and even more unlikely that consciousness is nonphysical, I conclude that there is a very low chance that they can be considered a "mind" with a consciousness that is aware of the pain and stimuli they receive.

The overall system is also extremely simple, in relative terms, considering the kind of AI code that's normally discussed around these parts.

We're already pretty close to making game characters have believable reactions, but only through clever scripting and a human deciding that situation X warrants reaction Y, and then applying mathematically-complicated patterns of light and prerecorded sounds onto the output devices of a computer.

If we can successfully implement a system that has that-function-we-refer-to-when-we-say-"consciousness" and that-f-w-r-t-w-w-s-"really feel pain", then it seems an easy additional step to implement the kind of events triggering the latter function and the kind of outputs from the former function that would be believable and convincing to human players. I may be having faulty algorithmic intuitions here though.