Hola-
I'm a frequent traveler aboard short-haul flights including the SAN-LAS route and usually there's a significant chance that a possible bumpy ride will end up scrapping the in-flight snack/drink amenities. The keyword is possible. If questionable weather or possible air turbulence is reported to the Flight Captain, they will then make the call on whether the Flight Attendants can serve or to remain seated. This is similar to the fasten seatbelt light being left on during cruising.
More often than not on short-hauls, the Captain will feel that the seatbelt light needs to remain on during the flight through the cruise altitude even though there may be limited or no actual bumps. It's possible that a bumpy ride was reported but there have been times that the real bumps never actually showed up. However if the weather or wind conditions reported to the cockpit is questionable, then safety comes first. The captain would decide to leave the seatbelt light on and may direct the Flight Attendants to remain seated. I don't think lack of service is done willfully. Trust me, I've been on flights where the Flight Attendants were asked to remain seated but the actual bumpiness of the ride was less bumpy than riding on a train but the injury risk would be too high to just "go for it" unlike walking through a moving train car. Best to play it safe and don't mess with the weather.
If you have a drink coupon that went unused due to an airline-initiated action, it doesn't hurt to give Southwest Customer Service an email or DM via Twitter/X to describe the situation and see if its value can be applied toward a future flight.
https://support.southwest.com/helpcenter/s/email-us
