That doesn't really sound that bad, considering that rides can easily cost dozens of dollars. Just about any other non-tech business would kill for such low overhead.
Other non-tech businesses, hell EVERY business that I've ever worked in that used AWS did better per transaction - healthcare, digital advertising, virtual office tooling, gaming. If you can't do better than a credit card processing fee per paid customer interaction across the company on AWS, you might as well be selling retail goods...and depending on age, your company might be soon.
Companies like Lyft are doing a lot more than updating a few fields for each ride. They would be processing massive amounts of location data and they are building out models to eventually use for self driving cars.