No warning lights, no problems, engine dead

Just wondering if anyone can help or has had a similar problem. My 2011 Altitude RAV4 just died. I had NO warning lights, no symptoms what-so-ever, no engine knocking NOTHING! I picked it up from a repair shop after a minor fender bender, no engine damage, drove it about a block and it just coasted to a dead stop. Had it towed back the collision shop, they had no idea so had it towed to Toyota service repair where they later informed me there was no oil on the dip stick, something about the oil pan and the engine seized. They said I'd need a new engine at the tune of 4-5 thousand $$. When I told them I had no symptoms of anything wrong, also confirmed by many who have driven my car and been in the car with me, they said that wasn't possible as I would have to have indicators saying there was something wrong. It had not been serviced properly and is therefore out of warranty (Australia).
How is this possible? I saw the forum discussion about the 2007 models having issues like this with the oil but from a 2011? Please if anyone knows anything about the computer system malfunctioning I would be greatly appreciative. Needless to say that kind of money is not something I can readily get my hands on