We disagree on what a working sewage system means. Tanker trucks aren’t it. Dubai may have had a working sewage system for a year now. Not great but better than I thought was the case.
Your definition involves strange mental gymnastics to turn a perfectly functional albeit expensive sewage system into a non-working sewage system.
The end user experience of the sewage system in Dubai is no different than in regular Western cities. That’s really all that matters when trying to figure out if it’s “working” or not.