Different methods are used in different areas.
Some areas the unit is on a pad at groundlevel. Most in Austin are that way.
Other areas it is raised a few feet to get keep a heat pump from being buried under snow. It may also keep grass clippings from being blown into the outdoor coils.
I'm sure more differences exist in practices. Heck, in some cities in Arizona, they install it on the roof.
Ask your friend, I'm sure he'll tell you why he chose the elevated installation.
I am for doing good to the poor, but...I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it. I observed...that the more public provisions were made for the poor, the less they provided for themselves, and of course became poorer. And, on the contrary, the less was done for them, the more they did for themselves, and became richer.
― Benjamin Franklin