You didn't mention the tolls to cross the Delaware River, but I'm assuming a taxi would charge them just the same.
However, I remember there was a PATCO/NJ Transit commuter rail station 2 blocks away, going back to the hub at the Philadelphia 30th St station. I'd imagine that would have been significantly cheaper. But, if I remember correctly, this fellow came from an area of the country where the first thing they think of is getting a car. I've seen this in NY as well- they get off the plane at JFK, go right to the rental car counter, and rent an SUV to drive into Manhattan. Woops, the parking garage refuses the oversize ride. Gee, toto, we're not in Kansas anymore. To be fair, I've likewise seen NYC people get off a plane and immediately go looking around for (nonexistent) mass transit at the arrival city.