Lying is typically considered wrong. However, it is often considered necessary to avoid unwanted conflict & to pacify customers. Where does this come from?
In short - customers are often willing to pay for a positive outcome. You fixed my car, thank you so much! Here's $350. No problem. You got my data back - here's $150! No problem. People are happy to pay for a solution.
For certain people, when they see how you fixed the problem, you have a new problem. 🙂 They will not want to pay, knowing how "easy" the problem's resolution was! If you wind up negotiating with that person for ten minutes, that's ten minutes wasted. If you have 300 customers a month and have to argue with 10% of them, that's six hours per month wasted that could be fixed with a small white lie.
It becomes easy at this point for the experienced technician to justify telling white lies to keep life simple, and customers happy. The problem is not in the white lies, it is in the decision to use them. Making this decision makes the decisions that come after it to lie more even easier.
Like with drugs, white lies, even just to keep someone happy without screwing them over - are gateway lies. Once you feel comfortable telling these lies, it will be easier to lie about everything to come.