Some people use those barriers. Some not only have a barrier, but clean it after every client with chemicals (thus exposing the client to petro chemicals and solvents), and still others use disposable barriers that they throw away after each client.
The incidence of bleeding during a treatment is more likely if the electrolysis provider is releasing ingrown hairs, but can happen with a stray hair or two.
What you are asking really comes to the point of should an electrolysis practitioner create an operatory that one could make computer chips in, and utilize all sorts of costly disposable (oil/petrochemical) products to add to their overhead.
It is possible to get too obsessive with these kinds of measures. Why stop at using a different cotton ball for every time you wipe the person’s skin. Why not change gloves as well? If you sneeze, change gloves and face mask too.
Should some infection control be used? Certainly. On the other hand, what this country and the world has as a larger problem, is the immune system compromising environment and so called food permeating the society, and opening up the door to increased sickness from previously non-threatening things.
One small example, a large part of the immune system is in the intestines, and the intestines need to move things along at a steady pace to keep the body healthy. What it needs to do this are fiber and water. The average organic food has 5 to 10 grams of fiber per serving, while the average processed food has 0 to 5 grams per serving, and a person needs a minimum of 20 grams per day. Same with water. The hydration deficit for the average american is a crying shame.
Later, when this immuno-compromised person gets sick, they will blame many things other than their years long voluntary immune system suppression.
Let me put the question back to you another way. Our society has now convinced toll takers to wear disposable (petro-chemical product) gloves while taking change, and airline and hospitality workers as well. Should they change gloves in between every person so they don’t pass on some pathogen from their gloved hand to the next person(s) they come in contact with?
It is an economy of scale.
Of course, the official response from the associations will be, Yes, they should be using all those barriers and chemicals as well.