Apartments are great:

• They have less outer walls to heat or cool.
• They enable densities that allow you to run errands by foot.
• They enable densities that allow you to access a wider range of services.
• The costs for things like groundskeeping get really cheap once divided onto all apartments.
• They are more affordable.

And if the walls are built well, you have just as much privacy as you would have in a single family house.