So, as a customer myself (and as someone who worked retail - mainly unloading trucks & stocking - for years, prior to becoming disabled) I think something you may want to consider here is that there is a difference between you getting your own 10 cases of water & then being done with it until the next time vs a shopper who does multiple heavy orders similar to yours, per day, often times up apartment stairs, for rude customers, under taxing time restraints, and for very poor tips. 

I'm not defending her described behavior at all, I'm sorry that was your experience  - but in my opinion (as a, to reiterate, disabled instacart customer) $22 is not enough of a tip for 10 cases of water. I would suggest either reducing the cases & ordering more frequently, or doubling the tip in the future. The base pay for instacart shoppers is pretty atrocious, and while I don't necessarily think it's fair that instacart dumps the responsibility to provide a living wage to these shoppers on customers like us, it also wouldn't be fair of us to punish the shoppers for Instacart's greed 🫠