Why did Georges Herpin choose a Greek term meaning tax exemption for the name philately?

In 1864, the French stamp collector Georges Herpin coined the term philately by combining the Greek words philos ("loving") and ateleia ("tax exemption").1

He chose the term because, prior to the invention of the postage stamp, the recipient of a letter was typically responsible for paying the mailing charges upon delivery. The introduction of the stamp shifted this cost to the sender, effectively freeing the recipient from the tax or fee associated with receiving mail. Thus, the stamp rendered the letter "tax-free" for the person receiving it, a concept Herpin captured through the Greek root ateleia.21