IVs are, while not the most complicated skill a medical practitioner needs to learn, a tricky thing to get right. Too deep and you risk causing real damage, too

IVs are, while not the most complicated skill a medical practitioner needs to learn, a tricky thing to get right. Too deep and you risk causing real damage, too shallow and you're not hitting the vein, wrong spot and you miss the vein, etc, etc. And most people wouldn't be happy with a needle permanently tapped into their vein, so not really viable.