Also, I don't know if you've ever had a job that's underpaid where you work with the public, but it's incredibly exhausting and frustrating and nothing like my comparatively stress-free job where I get to sit at a computer all day. Now imagine doing that in this moment of crisis where you're doing deliveries so that others don't have to risk themselves!
To your specific question, obviously something about Instacart will get more play on a tech site than, say, sanitation workers. I don't think that's odd. But there's no reason to assume that one needs to come at the expense at another -- if you start a thread about sanitation workers, I'd be first to upvote it.
As far as tipping goes, nurses are not tipped for their work. Nor are doctors. Tipping should not be part of the equation as it puts too much variability in the pay for these people. They should be paid based on the risk and the need for their work, not based on the whims of some people.
The market isn't whatever corporations tell you that you're worth.
Nurses and Doctors make a lot of money and have better health protection. At least, they have full health insurance, compared to food delivery drivers. On top of that, medical professional are expected to be at risk.
If you are coughing and you expect someone to risk their lives, by catching whatever you have, while delivering your food, then, be prepared to shell additional for your delivery.