The U.S. government backs FDIC insurance, which repays the first $250,000 per account if the bank goes under. I'm not aware of a bank without FDIC insurance, or of customer losses despite FDIC insurance. I don't see a difference in risk between them.
If someone is concerned about taxes on their high income, municipal bonds are worth a look. Federal and state governments do not tax municipal bonds, making their interest tax-exempt.
Very short term treasuries offer almost 5.4% right now, but anything over a year pays under 5%. The "inverted" yield curve means the longer the duration, the lower interest it pays (30 year being the exception). Here is the data from Bloomberg News:
United States Rates & Bonds