Because nobody wants radioactive waste transported through their town to offsite storage. (which doesn't exist anyway).
Remember the railcars scattered around a town after a recent derailment ? And here's the granddaddy of the type - an entire railyard destroyed. Roseville Railyard Disaster. They're still finding shrapnel 50 years later.
Woke me up 15 miles away!
Also an entire trainload of pesticides derailed into the headwaters of the Sacramento River a little later.
There will emerge a lot of NIMBYs if routine transport of radioactive waste is ever considered again.