Originally Posted by
MePlatPremier
For merchants a card-not-present transaction represents a significant risk. In the event of a chargeback it is on the merchant to prove the cardholder authorized the transaction, whereas if it was a card-present transaction (chip-and-pin or magnetic stripe) the onus is on the cardholder to demonstrate that s/he did not participate in that transaction.
Marriott does reimburse chargebacks to properties in these cases, assuming the property followed proper procedure when issuing the mobile key.
For places it is legal, properties have no reason not to be using mobile key in lieu of in-person check-in. They just choose not to.