I hopped into a Jeep Cherokee that I thought was mine and drove it down the road for a minute before realizing I was not in my vehicle. Keys are funny like that.
You'd think keyfob security would be worked out by now (just look at the prevalence of skeleton key software defined radios amongst the grayhat crowd). There's probably a limitation in security complexity due to limited power availability in the keyfob.
Ah, cool. Sounds like there's no excuse. My mistake.
I mistakenly assumed you'd need some kind of cryptographic key signing handshake via active electronics from within the keyfob to achieve secure comms with the host vehicle, and that such a requirement may have been some kind of implementation limiting factor, security-wise.