but i will say some time ago i flew a 172S which for some odd reason wasn't taking fuel from both tanks evenly (it had the G1000 suite so i had visual and audible warnings)
I feel unqualified to comment now...
I have heard although it might be an old wive's tale but seems to be fairly well accepted amongst the experienced pilots at my club that the fuel vent on a typical Cessna can also when airborne increase the air pressure in the left tank making it feed quicker than the right.
I am prepared to be shot down in flames and retreat gracefully.