What's the interest rate on your savings account?

Because the bank is buying Treasuries at ~1% or so and making money off of your deposits, and is likely only giving you 0% or maybe 0.05% interest.

If you've got $10,000 in the bank, that's basically a profit of $100 / year that the bank is getting from your account.

My interest rate is maybe 0.3%, so they're definitely making money on that.

But that's not a "fee." Obviously banks cover their operating expenses somehow. That doesn't mean they charge me to have an account or to deposit cash (in fact, charging for deposits would be counterproductive).

They do it directly or indirectly, I don't know how US banks works but usually over the world bank accounts vary accounts with no/low fees give low interest and vice versa.