In addition to the problems with your concept of the security model of locks that other commenters have addressed, I'd like to point out that while requiring un

In addition to the problems with your concept of the security model of locks that other commenters have addressed, I'd like to point out that while requiring unique per-person authentication tokens aids in per-user access revocation, it also leaks information, meaning that whoever can view the access logs can effectively track your comings and goings (or at least your comings) through that door. Keys which simply authenticate "I am in the group of people who are allowed to access this" are generally preferable to ones that say, "I am John Smith, check that name against the list of people allowed to access this." Also, keep in mind that Lockitron is obviously shooting for the consumer market, where concerns about sharing keys are basically non-existent. Commercial users who actually have to frequently deal with key revocations have been using RFID and other per-user access management technologies for ages.