This is "The Happy Breed" by John T. Sladek.
Machines take over the world and take over people's lives:
Nor were they limited to treat. The Machines had extensions clawing
through the jungles of the world, spying on witch doctors and learning
new medicines. Drug and dietary research became their domain, as did
scientific farming and birth control. By 1985, when it became manifest
that Machines could and did run everything better, and that nearly
everyone in the country wanted to be a patient, the U.S. Government
capitulated. Other nations followed suit. By now, no one worked at
all, so far as James knew. They had one and only one duty—to be happy.
Eventually the machines simply drug people into a state of comatose euphoria:
Looking out the window, he saw a bright pink- and yellow-striped
ambulance. So, the doctor next door was going off to a zombie-land,
was he? Or, correctly, to the Hospital for the Asocial. In the East,
they called them “Mussulmen”; here, “zombies,” but it all came to the
same thing: the living dead who needed no elaborate houses, games,
ink. They needed only intravenous nourishment, and little of that. The
drapes drew themselves, so Wattleigh knew the doctor was being carried
out then. He finished his interrupted thought.