This is a common sentiment but I don't think it should be the end of the story. So what if people from two hundred years lived significantly worse lives than ourselves? I didn't live then and I'm not a UPS driver. I have all the empathy in the world for people in harm, but the fact that suffering exist should in no way act as a counterweight on levers that tries to improve situations where relief seems possible.
And the first step to improving their working conditions is taking our own seriously.
Dunno about UPS fam, but I did work as a FedEx driver in my previous life... and nothing close to the stuff I see in our field. For sure, we are disposable in both fields. Perhaps the constant need to deliver X items on my route, but you get used to it because it doesn't really change. Our field changes all of the time and if you don't adjust you aren't hired. But I definitely didn't need to check my Slack, or stay up to date on current trends and tech on twitter, hackernews, newsletters, et al.