To get petrol and diesel they have to survey the land/sea, build oil rig, get rig in place, drill miles down and when they do hit oil they have to store on rig, transfer to ship, sail to port, transfer to refining plant, refine the oil in a very costly and time consuming process, store product on site, transfer to tankers, transport to fuel station and store in tanks to be fed to pumps.
Seems like the extracting of the hydrogen can be done without about 80-90% of those processes so not out of reach or too costly compared really!