This is not always true, most of Shinkansen track is concrete slab track, which is effectively fixed to the ground. And they actually do have special anti derai

This is not always true, most of Shinkansen track is concrete slab track, which is effectively fixed to the ground. And they actually do have special anti derailment guides build into the track to prevent a train from derailing during an earthquake: https://www.rtri.or.jp/eng/rd/seika/2006/01/safety_E05.html https://www.rtri.or.jp/eng/rd/seika/2006/01/safety_E05.html