It would be great if the CDC could focus on the actual wildfire we already have instead of the hypothetical non-existent cruising one. Cruising may not be a big deal to most, the big deal is the CDC's tunnel vision where they have only focused on cruising. Tunnel vision that has worsened the spread and costs lives. No other industry in world received any additional regulation by the CDC during this pandemic, a huge mistake that is proven every day when the positive cases area tallied up even though there are no cruises to blame for the results. Whether or not cruising should resume or if cruising is safe are other issues. My argument is that I find it hard to believe that more could not be done other than a cruise ban. So far that has been all we have received from the CDC during the largest pandemic in our lifetimes. Way beyond inefficiency.
CDC has published plentiful guidance for many industries. However, most industries do not fall under the CDC's lawful authority.
You've cited bars as one example. CDC does not have the lawful authority to regulate bars, they fall under local and/or state regulatory authority.
CDC's ability to actually regulate an industry is somewhat limited in the grand scheme of things when you look at what they are able to.
For example, the Vessel Sanitation Program (VSP) we are all familiar with - is the CDC program that "assists the cruise ship industry to prevent and control the introduction, transmission, and spread of gastrointestinal (GI) illnesses on cruise ships" (
https://www.cdc.gov/nceh/vsp/default.htm). Read the US Code that allows it (
https://www.law.cornell.edu/uscode/text/42/264 ) and see the constraints [for humans, for example,"shall be applicable only to individuals coming into a State or possession from a foreign country or a possession"; and overall the "Nothing in this section or section 266 of this title, or the regulations promulgated under such sections, may be construed as superseding any provision under State law (including regulations and including provisions established by political subdivisions of States), except to the extent that such a provision conflicts with an exercise of Federal authority under this section or section 266 of this title.". I think we would all agree VSP is a good thing, but it has its limits in law on what it can do.
Likewise, CDC is otherwise constrained in how much it can do.
They have the Federal Quarantine Act. They can regulate intersate and federal quarantine. They can regulate certain laboratories. There are some other places and things they can regulate.
But a bar ? A restaurant ? That is up to the state or local jurisdiction. The CDC can advise. They can put out guidance. They can strongly recommend. But it is up to local/state authorities to act. Or not. Its a core tennet of the US system of government.
So the CDC will regulate what is within its purvue to do -- which in this specific case is cruise ships.
But there is also regulation of international aviation. Relatively early on the number of US airports that could accept international flights was limited to certain designated ones, and various kinds of federal quarantine regulations were put in place for international travelers - including for example that even right now travelers from certain countries are not allowed to enter the US unless they fall under certain specified exemptions [the UK comes to mind as one so affected country].
Yes, they did not outright ban all international flights, because international air travel was deemed to be, in certain circumstances, still essential travel. Wheras cruising is deemed as non-essential travel.