Yes, on average the server at the high end restaurant did substantially more work, and they performed it more expertly.
they were better able to answer questions and offer suggestions (including off-menu changes that might help you). They timed your meal for your enjoyment rather than for turnover. They made sure you had fresh silverware, a clean table, and a full glass. They coordinated your bar, wine, and food orders so appropriate items were presented at the appropriate time. They verified the kitchen gave them correct dishes before they brought them to you. They devoted a lot of energy into ensuring that a small number of guests have a great experience.
They're able to earn decent livings because they are at the top of their field.
The folks at chili's are granted no autonomy. Their goal is to turn the table quickly, with the least effort; and to do this with the least skilled staff. They work hard, but their goal is to serve a large number of guests with a tolerable experience, not a great one.
Yes, they bring food and drink, but the focus is on throughput, not on quality.
It's similar to the difference between code written by a low bid contractor versus a talented on-site team. If you want anything unusual or if you care about quality and the experience, you'll greatly prefer the on site staff. Even if some execs might not understand why you can't offshore 100% of the work.