Wingtip Cameras : a serious conideration on the A380,I was told but if installing them as part of the design would have be relatively inexpensive (e.g. as part of the nav lights wiring ) retrofitting is a totally new ball game and pricetag.
ATC in apron, for info in most large airports today, the Apron control is not done by ATC anylonger , but by a separate (read much cheaper) airport subcontractor ,
Normally procedure do exist that after receiving a gate or push back clearance, if you encounter a problem and need to stop during the manoeuvre you have to inform Ground control. But incidents reports show that this is rarely done , because when this happen , there is generally a problem that requires the CREW attention.
As to the "responsibility " side of things the guy that hits something with 4 stripes on his shoulders is the one.
Follow me's , parking lamps marshaller or ground control errors will get you extenuating circumstances but not much more.