why can i not put more than 12 gallons of gas in it when it says its empty but it has a 16 gallon tank
Because you’re not brave enough to drive another 60 miles once the gauge reaches empty.
I agree. Just accept the fact that you have 4 gallons of fuel in reserve when your tank shows empty.
Have you never encountered this in other vehicles or is this your first vehicle. I suspect you vehicle has a dash read out that tells you fuel usage and miles to empty. I can’t remember that last time I saw my low fuel light come on. Frankly I don’t even see this as a problem.