That doesn’t mesh with how police shoot out actually play out.
An undercover officer doesn’t have the luxury of backup and are often outnumbered. Besides. This isn’t really a pocket watch sized pistol especially if it’s large enough for an accessory. I could understand if this was a micro compact pistol. But at this size and use case. If you need to fire it in anger more ammo per magazine is better than less.
I think you bring up another possibility. Many Chinese (and other Asian countries) police are still issued revolvers (if any firearm at all). Since firefights are highly unlikely with the limited number of gun-armed criminals, they don't really value high capacity (limiting collateral damage). Might be an alternative to revolvers.