Blindly repeating the bits actually works just fine. The relay doesn't need to know anything about the content of the conversation - it just needs to boost the signal enough that the car and key can talk to each other when they're far away. Neither key nor car are the wiser, as long as the latency is low enough.
I was unfamiliar with this buttonless setup. Seems silly.
The attack is defeated by keeping your fob in something that blocks radio frequencies I guess. Same idea as those metal wallets but this time for an actual threat.
