We can't park even partially on the side walk (meaning even on their driveway, as they are pretty short and we'd still be blocking part of sidewalk), if we do we get a hefty ticket. ($250.00 to $600.00)
Most clients we do normal street parking (parallel to sidewalk) and run the hoses inside. Having the reel in back means, at times no access to it, if parking is tight.
In addition PTO's have to be installed at an exact location and lend themselves nicely to a side reel. I only have a sliding side door, as at times (quite frequently) I'. parked right by a tree and would not be able to open a barn door.
When I had my Sprinter with a slide in, I had a back door wheel. Hated it.
I guess one gets used to equipment being where it is.