The people without a basic internet presence aren't likely to be customers anyway so it's not a huge loss. It's trivial to setup a basic account for any site that doesn't contain any personal data you want to keep hidden, if you aren't willing to do that, you're in a tiny minority.
It's equally trivial for a restaurant to set up a custom domain with their own 2-page website (overview and menu) on any of a hundred platforms that provide this service.
Most of these services are not free like FB, but any business that can afford a landline phone can afford a real website.
There are free ones as well, just as a subdomain (something.wordpress.com or something.wix.com), not a full top level custom domain.
Sure but they don't want to. If you want to see the menu they have online you need to follow their rules, not your own.
Obviously the restaurant has enough other customers and I have enough other restaurants to go to, so we both will be fine.
Sure, but putting their menu behind a trivial to access account shows they don't want you as a customer. You're the one complaining, not them.
I'm not sure why you think why people who don't have a Facebook account wouldn't eat at restaurants
And those 30 seconds are a harrowing pit of despair out of which comes the rest of your life filled with advertisements, tracking, second-guessing, and accusations of being a hypocrite.
Not that it means you should just make an account to make their tracking easier...
https://github.com/mikf/gallery-dl https://git.ao2.it/tweeper.git