There are different surface that can handle only so high of a temperature.
Fleet washing you don't want too high of temperatures or you can affect the paint, stickers, decals, etc....
Removing gum you want at least 180 or hotter water to melt the gum to remove it. Tests have been done at events and it seems like there is a lot of hype out there for how hot of water to use to remove gum. We tested a couple machines at the Vegas event a few years ago and it seemed that anything over 250 degrees did not remove gum any faster than 180 to 200 degree water. This was baked-on, out in the sun for many years gum in hot Nevada temperatures like we have here in Texas, they get hotter there in Nevada, a lot hotter so the gum bakes into the pores of the concrete and is harder to remove, even with hot water.
When cleaning buildings and houses you want ambient temperature water, no hot water as you can damage window and door seals, remove safety stickers and damage plaques and burn plants and grass.
When degreasing, you want warm to hot water but not too hot as you can damage equipment, wiring, computers, etc..... we want to heat the grease/oil to remove it from surfaces but not damage property where on concrete you can go really hot like over 200 or 250 or hotter and not damage concrete most of the time.
This is why my machines have adjustable thermostats, I need the different heat settings for the various types of cleaning I do.