I think it's not that hard of a problem in general. There are plenty of abandoned mines with tons of space where you can forget about it forever.
This has to be snark - Waste is never safe to store - the containment has to prevent leeching - over a lifespan of thousand, or tens of thousands of years
And it only takes one earthquake, or animal digging to completely upend that strategy
Then surely when they started pushing back on Yucca Mountain opening up, the federal government could have just bought one of the many mines that no longer produces, right? Why hasn't that happened? There are 49 other states that could, in theory, be bidding on a contract to house nuclear waste. There are some states that have a large amount of land relative to their population too.
For the record, this thorium reactor waste isn't harming anyone in Colorado, but they've also refurbished the plant in to a natural gas power station and it's still actively run. Should that be decommissioned, then I'm not entirely sure what it costs to maintain the waste storage facility. They're adding a couple new turbines to this plant so I expect it has a decently long life ahead, but what happens in like a century if DoE doesn't move this waste?
Regardless of the engineering, and I think we've made tremendous advances in nuclear design and have much better safety than before, I think it's more than low-information voters and regulatory issues, fundamentally we don't have a strong answer for the waste. A nuclear powerplant has a relatively fixed production life, but there is no end to the cost life.