There's a bit in Ubik that stays in my mind. Joe Chip gets into an argument with his apartment door that refuses to open for him because he owes it money. I kinda got that the door was an autonomous money-making agent that held him hostage - a conversation reminiscent of that between Doolittle and the Bomb in Dark Star. It made me see the ridiculous side and ultimate absurdity of micropayments leading to world where a dollar value is put on everything so that every silly little thing becomes a coin operated nuisance whose actual function is replaced by squeezing a few more micro-credits out of you.