Some homes have such large combinations of pools, fountains, 2nd small wading pools, etc., that require much more operating equipment than normal installations. Plus, the pool equipment has become so expensive, installing it in a concrete underground vault has become quite normal with homeowners that can afford it. It keeps thieves from stealing the equipment (quite a common thing today), and it is very quiet. Yes the vault gets dirty like the photo shows, but it serves the purpose for all of the above.
