From an htmx perspective, you would probably calculate things like that on the server. So the row delete button might have an hx-get="<delete-confirm-url>" that returns an HTML snippet with your modal content ("Really delete this car?") and then the button in that modal would have hx-delete="<delete-url>".

Of course you can still add vanilla JS with htmx, and/or send the car.rides_delivered value from your model as part of the initial page load, etc. You don't have to do everything with the hx- attributes.

In my opinion htmx is excellent when you have a state that can be easily managed on the server, because it makes it simple to get an interactive SPA feel while still keeping state on the server. I think a lot of the htmx fan base would argue that most web apps don't need to manage their state client-side and therefore don't need all the overhead of React, etc. But of course htmx isn't a cure-all.

You can check out the writing on htmx.org if you're curious to hear more of the author's perspective and goals.