And yet a ten year timeline is obviously nonsense. When these reactors were built in the 1970s, groundbreaking to power production was often 5 years.

Why is the process much worse now?

https://en.wikipedia.org/wiki/Zion_Nuclear_Power_Station

Yes, but it's also possible to go a lot slower than necessary. France converted their grid to 80% nuclear in 20 years and it seems to have worked out ok.