Consider a pressure washer.
It provides massive pressure at the nozzle, but the mass flow is still rather moderate as the water is just squeezed through a tiny hole. The suction on the other end is so low that it will not collapse the normal garden hose that is in no way designed to withstand negative pressure. A small hole requires a much larger pressure than a large pipe if the same mass flow per second is to go through it.
Same for the engines. If the set of small-diameter fuel injection nozzles are fed 3000psi, it is very well possible to feed the pump with a large diameter, low pressure pipe that both withstands a little boost pressure from the tank pumps or a light negative pressure when the tank pumps are out of service.
Since the 1959 accident to the GDR-built 152 airliner, there is no accident I am aware of in which lack of tank ventilation (in absence of icing) played a role in starving the engines.