I enjoyed this story, it picks up on the obvious threads for what a modern Auton story would be an executes it well. It takes a while for the Doctor and Ace to show up, instead starting with the retiree Roger Turner who has been recycling plastic and delivering to a new recycling facility. You're never surprised by where the plot is going, and there's nothing about the story that reads that it has to be this TARDIS team. Still, saying Autons are using the microplastics in people to control the human race and talking about plastic pollution? Maybe Praxes should've just been about Autons.