I think these people who can afford to go in a casino can also afford to pay for the cost, this is for the safety of people inside the casinos, so it doesn't matter if it's costly as stopping the casino operations just because a carrier has entered the place and infected the people inside is even more costly.
A simple statement. If only it's easy to do as it says.
For a gambler's mindset, why should they undergo a swab test just for the purpose to enter the casino? If I'm a gambler I'd rather find other casinos with no restrictions like that unless I'm a die-hard player of the said casino. It's no different from other establishments wherein there is no need for a test.
Again, I'm with the idea but I will give a 0% chance for that to be implemented or even considered.