The actually objectionable bit is that these jobs traumatize people over time, and desensitize them to the disturbing content they watch as a part of the job. Would I choose this over spending my day out in the heat, trying to sell food, snacks, or other wares, subject to the risk of pedestrian accidents or violent theft? Maybe?
Ideally there could just be better jobs available all around, but some people who live there might consider this at least somewhat better than some of the alternative jobs they'd otherwise be working.
Our current way of building models requires a large training data set that is already tagged/classified by humans. Unless the technology somehow improves so this is no longer necessary, these jobs are necessary. One bright spot is that once these models are trained, then humans can be out of the loop, which is certainly better than not having the models at all, and having to employ people, in perpetuity, to watch all of this content and directly make moderation decisions.
But perhaps the question we should be asking is: should we just completely do without, and never subject people to these kinds of jobs, no matter what the purpose? Maybe video, photo, etc. sharing on this scale just shouldn't exist if we have to put humans through miserable work in order to do moderation. But I don't really see this changing. So if we continue to employ people to train our AI models, can we get to a point where our future models can be used to bootstrap/train more sophisticated models, without the need for further human classification of the training data?