There are property taxes in the US, they are levied on the appraisal price of the property, not on the living area. You know the price is reasonable from the comps. As you're overestimating or the appraisal is already at the legal cap (in case of taxes) you don't really care about the living area.

There are no US-wide property taxes. However, almost every home in the US has to pay property taxes to at least one level of government. That's what pandaman was referring to when they said the city (which would be levying the taxes) would want the footprint overstated so they could get more tax revenue

Well technically, if anything, overstating the area available for rent would increase the paper value of your property, and thus usually your taxes.