You can "expect" anything you like, but the phone industry is absolutely huge and Apple is just a tiny player. Corning does work with Apple, but an advance in materials science like glass that is both harder to scratch and is more shatter-resistant would be a cash cow for Corning and they would sell it to Apple and every other phone manufacturer. (Likewise, if some other company figures it out before Corning, they can pretty much drive Corning out of the Gorilla Glass for phones marketplace.)
An even better example than auto insurance is automotive "clear bras." Most people purchasing a higher-end car wouldn't drive the it off the dealer's lot without one - but many people do. Those that do often have stone chips on the nose of the car by the time they get it home. Sure, the car company could apply one at the factory and charge you a lot for it, but most prefer to choose their own, it's up to you.
You don't have to use a screen protector, I know people that don't, but you need to use extra caution and/or a case that provides its own.
Ceramic Shield increases the strength of the glass and it actually is more scratch-resistant than the glass on the iPhone 11 family of phones was.
You can use your phone without a protector, and the ads are not lying to you - all the items you see in the ad are softer than Mohs 5.5 or so - pennies, miscellaneous items, even many car keys. Bits of granite or steel, not so much.
So you can use your phone without a screen protector, just as you never have to wear sunscreen as long as you are cognizant of how long you've spent outdoors.
Whether you need to use a screen protector (or for that matter, sunscreen) is completely dependent upon your lifestyle.
I've never used any iPhone - and that means going back to the original in 2007 - without one, as it's cheap insurance.
What you choose to do is up to you.
Would you feel better if Apple Stores acted like car dealers and tried to upsell you on a bunch of accessories before you left the store?