That’s due to the Uniform Time Act of 1966, which stipulates states can’t unilaterally act on DST without federal approval.
However, the law permits states to remain on daylight saving time year round, which is why Hawaii and most of Arizona don’t participate in the twice yearly clock changes.
Which way is it?
I think the idiot TV-station “journalist” meant that states can stay on standard time year round, but not on daylight saving time year round. I don’t know about Hawaii, but Arizona (except the Navajo Reservation) is on standard time year round. I like it better that way. In the summer, I just want the sun to go away at the end of the day, not hang around for another hour. I’m always up by 3 or 4 am anyway, so I’ll get the benefit of the somewhat cooler mornings without having to do anything differently.