”UK... I don't pay any fees for banking.”
True , you don’t pay any fees.
You simply pay all your money into your account every month and the bank leverages that positive treasury position on the money you’ve lent them to play the stock marke until you need it back, at which point they give you back only what you need without any recompense for the loan you’ve made to them.
“Free”. Dream on. It’s like the “free” iPhone you get on a £50/month mobile contract.