Also, despite my 30+ years on this Earth, I vastly more trust a 'professional' shopper to pick out good veggies than I do myself. I respect that you're different, but I can say with 100% certainty that the produce picked out by my instacart shoppers is excellent and better than I could do. Never a single complaint there, at least from me.
Do they really rush? From my side, they seem to take their sweet time. They text frequently, asking questions, suggesting replacements not shown in the app, etc. The whole process feels slow and relaxed.
I don't eat meat so I don't know about that. But I would assume the same as veggies. Instacart does a top-top job picking quality ingredients for me. Definitely better than I would know how to do myself.
Who is more likely to know the freshest spinach? Not me, that's for sure. An instacart shopper who is there all day? Much more likely to get good results.
I do have issues with instacart, but none of the concerns you've mentioned have in any way harmed me. My main issue is that the delivery times seem to be not communicated to the driver. So it will tell you 10am - 11am, but the driver will show up at 9:50 and not know that they are early. Sometimes also, the selection available on the website will be mislabelled in category (tomatoes in bath care, or something).
Otherwise it has been really incredible for me, overall.
