The radars are not the problem... the problem is the people been alert as to what the radar shows...
With the Aegis Combat System which includes the SPY-1D radar, the personnel behind can see what's going on around the ship, up, down and sideways but the system has to be monitored by human beings otherwise if set "automatic" it would had, long before the collision, launched torpedoes, missiles even the garbage cans (LOL) against the tanker as it would had treated the tanker as a "present and clear danger".. !! IMO
I guess we have to wait until the final report is aired to see what actually happened and why.
Having fun on other people's demises is sometimes like throwing a boomerang into the air and walking away from it pretending it's not coming back.