I disagree with you on that. I have seen some films of Japanese standing on docks or levees so they can watch the tidal wave come in. They can run pretty damn fast when it does.
I believe you're referring to the pics that were all over the internet and falsely labled as from the December Tsunami; they actually were from a "Tidal Bore" (which is a regular occurance at high tides and the timing is known in advance) going up a river in China; that particular time it was unusually high and people had to flee from their vantage point.
If existing, negligible numbers in comparison with (some of) those in the US who ignore warnings. The photos take may in fact have been taken before the 'clear out' order was given by the Japanese authorities.