This is the reason I refused to use Amazon Fresh. I'd rather pay higher subscription prices like with Prime as opposed to tipping every delivery. Even if it's optional, just the existence of the tipping feature adds social pressure.
Last I checked for Amazon Prime Now, drivers are only aware of their tips in aggregate, so leaving $0 is putting pressure on Amazon to pay their drivers more. It's kindof shitty, and I don't use the service often, but if Amazon is going to give me an option on who is going to foot the bill for the driver, I will pass on that every time.
I'm aware of that, and personally it doesn't matter. It only lessens the social pressure. It doesn't eliminate it.