Honestly I hope people do get charged for spamming alts just so they can do 48-64 leves per day.
How could they even benefit from that? All the exp/rank/gil would be split between all those characters. Even if they trade all the gil earned to one main character, they are still losing out when they could have Leveled/Ranked one character up to where leves start giving a lot more gil. Have you heard of Leve-sharing?
It is a viable option for people hoping to try out other starting cities and characters without deleting/recreating multiple times. Hardly any benefit otherwise except maybe as a mule. I don't think they should be charged if they decide not to keep them past the 30 day free period either way.