yes, in the US shipping regulations are written with the vessel owner in mind first and the ATB concept is one which is in place to benefit the owner by offering approximate ship performance with a significantly reduced manning cost since the manning level is determined by the tug’s tonnage and not the combined unit. I would hope that the USCG might someday revisit their manning requirements to both increase an ATB’s manning levels and to lower a small ship’s (<10000grt) manning to bring the two closer together. Then you might actually begin to see fewer ATBs built and more small ships. I feel that the owners would be very glad to be rid of the added costs to build an ATB over a small ship and like the better performance without the potential of losing a tow in a bad place.
now why ATBs are not in widespread use worldwide is that the regulations in other nations are such that there is not such as savings in manning as in the US. also, the ATB concept is not great at all but they do work. I know of no casualty involving an ATB in the US resulting in significant pollution specifically because of the fact the unit was of an ATB type although we came extremely close to having one in this recent loss of the tow off the BC Coast. Harley just got very, very lucky in this instance and if the barge had grounded and spilled its load, you might see a huge cry to ban them because of their weak link in the connection arrangements.
lastly, the tug you showed is not an ATB at all but just a tug pushing ahead which is used all over the planet including the US. There is no mechanical connect between the two vessels, only lines.