You’re getting less return (a little over 0.5%) that you’d be able to get by buying Treasury bills, which are also exempt from state income tax. By basically letting the bank do that for you and skim that half percent off the top for themselves you get much more liquidity and quality of life. This is how all savings accounts work—Capital One and others offering higher rates versus the 0.5% APY a lot of big banks give us them accepting less return on your banking business in hopes of getting you entrenched in their ecosystem.

Brokerages like Fidelity do offer auto roll service for Treasury bills which helps with the QoL issue, but your money still won’t be available at a moment’s notice like it would be in savings