You need to add a couple of other factors to mix-zoning (or no zoning) as well though. Houston, for example, is a no zoning city - you can buy a commercial warehouse and turn it into two lofts between two chemical plants if you like, and no one can stop you. (Effectively.)
However, the abundance of inexpensive land means its cheaper to build "out and flat," than "in and up," and the rush inwards that has been occurring over the last handful of years (Midtown, Montrose, Heights, EaDo, etc.) has been countered by plenty of new subdivisions and an 18-lane freeway, along with plenty of 6-8 lane freeways. Then again, we have precious little public transportation, and any expansion is usually looked upon with disdain.
However, the abundance of inexpensive land means its cheaper to build "out and flat," than "in and up," and the rush inwards that has been occurring over the last handful of years (Midtown, Montrose, Heights, EaDo, etc.) has been countered by plenty of new subdivisions and an 18-lane freeway, along with plenty of 6-8 lane freeways. Then again, we have precious little public transportation, and any expansion is usually looked upon with disdain.