Flow, not just pressure
Pressure is only half of it. The amount of water a machine moves, its flow, is what carries dirt away. Professional machines move far more water than small consumer units, which is why they clean faster and more evenly.
Surface cleaners
A spinning bar under a hood cleans flat concrete evenly. It replaced the wand-only method that left stripes on driveways and walks.
Soft washing
Dedicated soft wash systems let roofs, stucco, and screens be cleaned with a solution at low pressure instead of being blasted.
Hot water and reclamation
Heated water handles grease and gum, and reclamation equipment captures wash water on commercial sites that require it.