These tools have not shown decent efficiency, the root of the fuel theft problem, unfortunately, is not always a low salary. This is a social norm, like "solving a problem" on the roads.
Historically, no one aspired to change anything. At the same time, bans and fines are not a tool, but an irritant. The most that, for the most part, what an employer can do is to fire an employee. The judicial system, in most cases on the side of the employee, therefore the only sure way is not punishment, but the creation of a system in which theft is easily detected and high-quality and impeccable work is rewarded.