The term essential involves a calculation of risk and benefit. Campgrounds are housing for some category of people, their owners will go broke without customers and as outdoor facilities, the are very, very low risk.
Risk in this case derives from some combination of proximity, time and expected behavior.
People pass through liquor stores and banks for minutes at a time. Same with most businesses characterized as non-essential. That lowers the risk a great deal. From that perspective, you cannot distinguish them from grocery stores.
While I think it's ridiculous, my insurance company considers acupuncture a sufficiently important health service that they pay for it. That puts them on the positive side for benefits. Though the experience takes time, as a medical business, mask compliance is expected to be high. Lower risk.
Churches are like bars. People go there, stay a long time and engage in risky behaviors. Any mask that is not professionally fitted is going to allow plenty of virus laden particles out of each person when they are speaking in tongues, singing or whatever other stuff they do.
Close proximity means that someone else can readily (again, unless the mask is professionally fitted it's a risk reduction) not elimination) that someone stands a decent chance of inhaling it.
Further, liquor cannot be made at home. Nor can food or bicycle parts. God, otoh, can be worshipped anywhere. Your imam can council you with zoom. The calculation of essential includes, or should include, whether or not the good or service can be made available otherwise.
Also, the economic harm to the proprietor. Synogogues might have a claim of harm over high holiday ticket sales (an appalling practice) but I've not heard of many others selling tickets for services.
I think that Sunstein is right. This is not an important advance of conservatism. It is much less awful than decisions for Hobby Lobby, Little Sisters of Intolerance, etc.
However, it does signal two awful things. First, it shows zero deference to local authorities in dealing with a life threatening pandemic. (If this was in the future and the test positivity rate was not skyrocketing around the country, a different balance would occur even to me.)
It was implemented as a preliminary injunction exempting religious types from public safety rules. This is usually done based on some idea of irreversible harm. They have just said, "Sure you say you're so-called scientists say this is important to avoid death but death is only bad if you can't go to church." Fuck off, atheists, live in their pandemic.
Second, the establishment clause has become like the second amendment, a death wish for democracy. The Religious Freedom Restoration Act has to be repealed for democracy to function. Gun control has to be possible. We have to find ways to stop these lunatic interpretations of the constitution.
None of this will happen because the Supreme Court, while not signaling a new conservative extremism today, has signaled that human lives do not matter compared to observing the faith. They have made clear that practicality plays no role in their justice. It's easy to imagine that the machine gun prohibition that was perfectly legal in the nineties will be overruled if it happens today. I have no doubt that it is now legal to shout Fire! in a theater.
They have signaled that they think it just and fair that all of us die for principle, even insane ones, as long as you can tie it back to something they love. Freedom of religion never seems to include my freedom to worships zero-religion unimpaired.
i'll add finally that they also chose to prohibit this as a preliminary injunction done without a fact record. Had they asked, Cuomo's experts could doubtless have explained real facts instead of my ignorant and imaginary rationales. The emergency isn't dying sick people. The emergency is that people can't go sing religious songs at each other. It ridiculous.
The real emergency is right-wing religious nuts taking over our country.