Why is the bias current for ADG1438 multiplexor so low?

opampsmoker said:

Hi,
ADG1438 only draws a few uA from its Vcc and Vss pins. How can it be so low?
It only draws up to 420uA from its VL pin.
Again, how can all these analog switchs be actioned with so little current draw?

ADG1438 datasheet

https://www.analog.com/media/en/technical-documentation/data-sheets/ADG1438_1439.pdf

Click to expand...