

This would be easily mitigated by the keyfob using a rolling code. The attacker can record the signal, so the car will also have received it. A replay of that specific code won’t work again. That is a principle used in cheap garage door fobs for many years. So I guess keyless fobs would have at least that level of security.
Better would be a cryptographic encryption using public/private key (already done in chip cards, so common technology). Though - looking at the dumb things car manufacturers did - I wouldn’t be surprised if they didn’t use private/public keys for this.
Surely not relevant in this case, but in the german novel “The 13 1/2 lives of Captain Bluebear” (by Walter Moers) a Bollock is a giant, very dumb creature (as in multiple km high), who at some point in his life takes his head of, puts it on the ground and spends the next centuries searching for his head. I think that is funny.