You are charged redemption fee because you allowed your domain to expire beyond the grace period for renewal. Thus, the registrar has to pay a fee in order to pull it from redemption with the registry. This fee is only being passed on to you for the late renewal.
For any domain name that has entered the Redemption Period, the registrar must pay a fee to the registry. The registrars typically recover this fee through a charge to the Registrant requesting the redemption. This is the rule for any domain under ICANN and the rule is applied to every domain company in the world. The only way to avoid redemption fee is to renew your domain in time, on/before expiry date.
For more details, visit http://www.icann.org/en/resources/registrars/advisories/deleted-domain-restoration-fees-17dec09-en.htm