It's kind of a modern take on boarding houses. Actually, I think that the optimal situation is much closer to a boarding house.
Take 10-15 units, remove the kitchen and laundry entirely. Use the savings to pay a full time cook and laundry staff (2-3 people) to cook at-cost meals and do laundry.
In many apartment buildings in southeast asia (especially those that cater to foreigners/wealthy immigrants) there'll frequently be a shop and a small restaurant at the first level that mostly caters to the people who live in the building. No reason we couldn't have something like that here, though admittedly the cost of running both those types of services are probably pretty high given regulations. Expect a lot of politicking at the condo boards though.
The math may well work out differently for a family of four.
Tax land. Tax capital gains on land. Untax labour.