If we assume the rental car isn't prepaid, if the friends can pick jrl767 and Mrs jrl767 up at MSN, a rental car might not be needed, so that would mean savings on the total cost. Depending on the plans, taxi/uber could work if a long drive from the airport is no longer necessary.

OTOH, when arriving late into MSN during a snowstorm, I wouldn't want to count on taxi/uber working well. It would be more more convenient if someone is willing to drive to the airport to pick them up.