It's because every time safety fails, we find a way to solve that problem, and solving it costs money. Sometimes a lot of money.
So Chernobyl absolutely confirmed that containment buildings are not optional. Fukushima resulted in increased requirements for availability of backup power in case of a disaster.
Solar and wind don't really have that, because if a wind turbine falls apart in a hurricane, it's not really significantly different from any other random structure doing the same thing. Being killed by a chunk of turbine blade in a hurricane is not different from being killed by a chunk of a house, and in general not very likely because they rarely have people living right next to them. So we don't demand that wind turbines can survive anything nature can throw at it.
Disaster cleanup is a problem for sure. I think it’s still cheaper than oil and gas because those industries externalize all their costs.
Look. I’m not against solar and wind. I just think nuclear is the only way to feasibly rapidly decarbonize our energy production and solar and wind proponents always ignore that solar and wind just can’t do that on their own. Yes grid scale batteries are being invested in but it’ll take forever to build enough capacity assuming we even can in the first place - a not insignificant portion of battery production overall has to go to vehicles too and there’s no sign we’re getting our shit together to use car batteries as part of grid scale storage (the electrical distribution aspects are very difficult)