Full Self Driving means that the car is capable of driving itself, not that it can handle all situations autonomously.

A counter example, the package of Cheezits says "made with 100% real cheese", even though they are not 100% cheese, cheese is the 3rd ingredient, below flour and oil, but of the cheese used in the product, it's 100% real cheese. (so it makes it a meaningless statement, I guess they mean "no artificial cheese flavoring")

That's not a very good argument: "made with" implies that it is one of several ingredients. If Cheezits said "made entirely of" then the consumer would be understandably confused if there are other ingredients. Think about what you would answer to the questions "Did you make this pizza WITH sourdough?" vs "Is this cake made entirely OF lego?".

If the car can't "fully" self drive, then it shouldn't be marketed as such. Call it "partially self driving", "assisted self driving" or whatever.

That depends on your definition of driving, for example, take the dictionary definition:

"To guide, control, or direct (a vehicle)."

My car has driver assistance features, it can do basic lane keeping, keep a set distance behind the car in front (even in stop and go traffic), and has emergency braking assistance. But no one would say that it's self-driving.

Tesla FSD can control the car from entering the highway to taking your exit (plus some support for driving on smaller streets).

But it's not autonomous, hands-free driving.

I am not sure I understand the argument here as what you said highlights that Tesla's FSD is not fully self driving.

Taking the dictionary definition of fully:

"completely or entirely; to the fullest extent"

I would expect a fully self-driving car to drive for the entirety of any trip I wish to take. Anything less than that I would consider as "partial".

The car can fully self drive -- it has full control over steering and brakes, can pass other cars and even enter/exit the highway.

My car has limited self-driving, it can only do limited lane keeping or keeping distance from the car in front.

So you're defining it as the capability to automate steering, accelerator and brake? (i.e. the three things that constitute driving)

By that definition self-parking cars can also fully self-drive.

My definition of driving is being able to do all the tasks required to pass a driving test, i.e. driving around a city (intersections, roundabouts etc.), motorway, country road and car parks.

That’s clearly a bogus argument.

Made with 100% real cheese

Is clearly and unambiguously not the same as

100% cheese

But it is quite a good example:

A cheesit contains an ingredient that is 100% cheese.

A Tesla with FSD mode, is a car that has a feature that is full self driving.

If that mode cannot handle all conditions, then it is not full self driving. That means no “I’m confused” switch to a human driver.

Now explain the meaning of "Full".