So youre telling me that every Datsun thats been sold over the years has been in perfect condition? Not likely. A few problems here and there could be weird light issues, door bushings suck, some surface rust, AKA not a perfect car. Any 40+ year old car thats not a complete restore will have some problems here and there. It looked like that car was owned by a Dealer lot which Im sure doesnt have much Datsun knowledge. What may be simple for you and I to fix may be hard for them because they do know have access to the right knowledge or parts.
Unless the car sounded like an absolute wreck, I wouldnt have passed up on that. It seems like theres a ton of cars fitting the OPs description, but hes being too picky. People come here and do that all the time... I want only a 1968 Datsun, with no rust, original paint, has to be a 5spd, perfect interior, a runner, and within 15mi. of my house. Its not going to happen.
Once again, its a 40yr old car. I understand people not wanted a pil of rust and they want it to run, but eventually you need to put on your big boy pants and make a decision. There are plenty of nice projects out there for a decent price. Find one, build it how you want it, and enjoy.