Not true. The 1993 Hokkaido earthquake had waves reaching 31 meters. The 2011 one near Fukishima only had waves reaching 10 meters.
Just a stone throw away in Alaska, tsunami once reached 524 meters.
These things are going to happen, and plenty of these natural disasters would only get worse as climate change persists. To say because they rarely happens, so nuclear power plants do not have to put them into consideration is irresponsible.
Just from 1950 to now, Japan has had 3 tsunamis with waves over 10 meters. That’s 1 every 23 years. So what you gonna do when a 31 meter wave crashes into your power plant, which has to be built on the coast line?