Lots of reasons no doubt, as with many other of life's questions - it's expensive though, for one.

The best individual metric I'm aware of as a way to compare costs of different types of energy production is called "Levelized Cost of Energy" (LCOE) - here's a Feb 2021 report from the U.S. Energy Information Administration with a link to an estimated cost comparisons page:

https://www.eia.gov/outlooks/aeo/pdf/electricity_generation....