The welfare reasons go beyond what is obvious - e.g. vaccinations, grooming and vet trips.
Just one example is that sats need to sleep for at least 12 hours a day, and like humans struggle to do so in loud, bright environments like cafes - let alone with excited humans who are in the room specifically to see them.
Sure, some cafes have back rooms and hours when not open to the public. But in a large, multi-cat environment, not every puss will be on the same sleep schedule and they'll still have playmates to deal with.
What's worse, is that when a cat feels stressed, they will often fake sleeping so as not to draw attention to themselves, making it really hard to monitor how much rest they're getting.
Not getting enough sleep can make cats incredibly ill, and lead to severe behavioural issues.
So in comparing the environment to a city centre apartment, it's really not the same.