As others have mentioned these workers have so little leverage right now because of the massive unemployment. So even if Amazon was to charge customers more, they could totally just pocket the money and the warehouse/delivery/grocery people would have no position.
It's so completely unfair. Everyone risking their lives to feed us right now should probably be making 2-3x normal pay (and we should be paying a lot more for their services).
The vast majority of people in modern militaries will never see combat. They are all somewhere relatively safe and merely supporting that small minority of troops who will see combat. Consequently, it is no surprise that pay is fairly low.
But in the private security world – people guarding Western and Chinese interests in unstable developing countries – those people are likely to get involved in some shooting, and so their salaries and benefits for loved ones are very high.