You are assuming you only have 2 choices, single-family home or apartment. That's a very American perspective because most of America only allows those two but in a proper city you have townhomes, duplexes, casitas, bungalows and many more options that aren't just apartments. However, most of American is zoned exclusively for single-family homes and not mixed-use so like the parent comment said, you don't get benefits of proper density which includes many home types.