They probably do, I think it's the U.S. Senate that doesn't (which is why it has the nickname Senate Launch System).

It's not like NASA hasn't been launching rockets in the time since Apollo or STS. SpaceX has spent upwards of 10 billion dollars on the Starship program, with a finished product still not on a launchpad. SLS is the largest rocket ever produced and will cost an insane amount of money, the actual price for this launch is actually around 4 billion dollars according to NASA itself.