When you make an appointment to see the vet, you do see the vet. The tech will come in first usually and get a temperature, weigh the pet, things like that. Then you consult with the vet. If he/she orders blood work or wants to give a shot, the tech will come back for those things.
In some vet offices, you can make an appointment just to see the tech if you don't need to see the vet. When I needed to learn how to give fluids at home, it was a tech who taught me.