If the restaurant pays you less due to the expectation of significant tipping, then I do have a bit hard time too see why the practice of Instacart and restaurants differ that much. I guess you need to be American to understand this tipping logic.
Instacart is dynamically adjusting down wages in response to tips; restaurants have a fixed wage, with a legislated minimum — even if it accounts for average tips.
The difference is that one allows the customer to dynamically adjust the wages in response to service; while in the other the company is pocketing that variance themselves, rather than passing it on to workers.
It’s simply fraud to pretend one situation is the other — there’s a distinct and meaningful difference in who pockets tip variance.