There are literally tens of thousand of dams, if not > 100k, worldwide (over 22k in China alone), with well over a century of major utilisation. Granted 100 or fewer major (2+GWe) installations.
There are fewer than 400 nuclear power stations worldwide (3911 by my count from Wikipedia: https://en.wikipedia.org/wiki/List_of_nuclear_power_stations...), the bulk in operation for less than 50 years. We've had three major disasters and numerous close calls, all with massive long-term consequences. Building out infrastructure to the scale of present or future (industrialised-world electric provisioning to 8-12 billion inhabitants) would see even at much better safety records* a major accident every few years. And that's only one disadvantage.
Notably, once floodwaters recede, even a catastrophic dam failure returns to livable condition rapidly: weeks to years, rather than centuries.
And, as noted, it's human, social, business, and organisational factor common to any major high-value asset technical project generally to blame.
(This was not a large value of 400.)