Actually, that is true ONLY if the capacitive sensors run from the bottom to the top; if they are bent to go from the wing root bottom skin to the wing root top skin, the sensor will only read the bottom 40-60% of the tank and show full above. The other way to be able to measure from full to empty is to use two sensors, like the Cies brand, in each wing.For those of you building new tanks, tha capacitive senders are nice because the fuel gauge works from the very top to the very bottom. the traditional senders dont start reading until 3 gallons down.
But if one puts a conventional sensor in the tip of the tank, along with in the bottom, then the EFIS can be calibrated to give accurate readings from the very top to the very bottom.