The pitot is an interesting device.
Along a streamline it takes the sum of kinetic energy
and static pressure, and recoups that kinetic energy
as a dynamic pressure contribution.
In the transverse direction of the same air parcel,
the (sidewards) static vent only collects a static pressure (or lower.)
Makes a good way of checking the stream velocity
by comparing these two pressures.
This is like considering the pressures due to flow in a pipe
in transverse and longitudinal directions - only inside out!