I have a theory: From reading a bunch of case studies, it seems that the main route of transmission is microdroplets hanging in the air. A huge majority of transmission comes from being near someone for an extended period of time (30 min or so) indoors.
Since smoking is allowed in most casinos, they have extremely powerful ventilation and air filtration systems, so that their non-smoking customers aren't excessively bothered. If you've been in a Vegas casino and seen someone smoking, you notice that the smoke almost instantly gets sucked into the ceiling. This may dramatically reduce transmission in casinos or other venues that allow smoking.
Since smoking is allowed in most casinos, they have extremely powerful ventilation and air filtration systems, so that their non-smoking customers aren't excessively bothered. If you've been in a Vegas casino and seen someone smoking, you notice that the smoke almost instantly gets sucked into the ceiling. This may dramatically reduce transmission in casinos or other venues that allow smoking.