Surely you don't mean yearly car registration, driver's license fees, gas taxes at the pump, liquor taxes on booze or any other daily sales taxes they pay. So are you referring to the lack of property taxes they pay? I'm assuming the landlords are paying those.
Taxes are probably the wrong way to think about it. More important question is does lower class people produce net positive effect on economy in general. If they do then subsidising them producing enough lower class people to replace ones producing values will likely make sense.
Now if they are net negative, we get in much murkier waters...