Re: If all thats required.............
"they benefit the massive reduction of transport costs for goods and services"
Sorry, one of the biggest costs involved in trucking is FUEL, and then maintenance [brakes, tires, etc.]. Wages are a part, but it's much smaller than you might think.
Independent truckers make a profit, sure, but it's a fair bet that half of their revenue is burned up by the engine in order to deliver the stuff. If a trucker earns the equivalent of $50/hour in profit (probably not likely, just using this number for example), his fuel burn rate could be nearly the same [particularly on long haul]. 5mpg might be consdered very very good mileage for an 18 wheeler. At $3/gallon and 60mph [both a bit unrealistic in places like California], that's at least $36 in fuel per hour for "straight and flat". Factor in some hills, stops [and waiting] at weigh stations, plus the truck's maintenance costs [which are the same for robo-drivers] and it's not so much of a savings any more...
And since fuel is much more expensive on your end of the pond, my numbers for "middle america" are a 'best case' scenario. It's a fair bet that fuel costs in EU and UK are considerably higher than this.
THEN, consider that the truck drivers are likely to load and unload their OWN trucks. Having extra people on the dock to handle the loading/unloading of robo-truck might not be so economical. There'd be several employees there, working in bursts, and coking/joking/smoking the rest of the time.
Overall, I think robo-truck would be "a wash".
One more thing - for REALLY long hauls, freight trains are typically used. They stack them with pre-loaded truck trailers. So the trucks bring the trailers to the rail yards, or within the state the rail yards serve. The trains then take things everywhere else. In some cases, the 'trailer' is a shipping container with wheels and a hitch bolted on. So they're already being really efficient, if you think about it.
And the driver's wage isn't all that much, when you look at everything.
[I think I'd rather have a skilled driver anyway especially for traveling in mountainous areas]