I would assume the amount they make is a percentage of the cart total. That would be the only way to make longer trips worth it. So that would incentivize suggesting more expensive options. But I imagine there’s also a tip mechanic so doing obvious stuff like that could hurt your tip.

In these cases, I give them the benefit of the doubt and try to provide a rational argument why I disagree with them. It either sparks a discussion/debate or they’re obviously trolling and I downvote and move on. But some people that seem like trolls are really just ignorant and showing them why you disagree can help them shape their opinion.