I must obey my master.
Apparently Palpatine had instruments to blow Vader up at will...
Episode 1:
-before the race-
Shmi: "All the slaves have a transmitter placed inside their body somehwere" { So they can be tracked?}
Anakin: " I've been working on a scanner to try locating mine." {good for you}
Shmi: "Any attempt to escape..." {Not many are there?}
Anakin: "And they blow you up, boom!" {Interesting...}
JarJar: "How wude!" {My thoughts exactly}
-After the race-
Qui Gon: "And he has been freed" {When exactly?}
Anakin: "What?!" { He doesn't know???}
Qui Gon: "You are no longer a slave." {really?}
Anakin: "Did you hear that?!?!" { So no transmitter-recovery made?}
Episode 2:
ObiWan: "Thats Anakins tracking signal, but its coming from Tatooine..."
{So he still has his transmitter on.}
So Luke could have defeated Vader just by visiting Wattos shop to buy a transmitter to blow Vader up. At no point did they remove it from Anakin in the films.