Sure, but it’s a private coffee shop, and they can just simply not let you in without paying or in headphones. They need to make money.
So, at first your clever trick works. But once everyone is doing it, their advertisers stop paying them, so now someone’s gotta pay for the coffee somehow.
Why did the coffee shop have a “Free coffee and unlimited sitting time” sign in front of it?
No it didn’t. It said “entry for free, coffee either for money or with ads”.
So then there are some ads playing in the background and I put on my headphones so that I can ignore them.
Sure, but it’s a private coffee shop, and they can just simply not let you in without paying or in headphones. They need to make money.
So, at first your clever trick works. But once everyone is doing it, their advertisers stop paying them, so now someone’s gotta pay for the coffee somehow.