I knew an adjunct who, in the words of the department head, was fired for being too harsh on cheaters.
I've caught a few people cheating, but I usually fail them for the assignment instead of the class and spend extra time working with them to get their grades up. I've only had one repeat offender and I enforced the rule. The student came up to me a few months later and thanked me. Said it made him re-evaluate his commitment to school.
My mom is a retired high school teacher, and it's a completely different story. Among the "perks" in her contract were legal representation and liability coverage.
When I was an undergrad, certain ethnic groups were untouchable on the campus. There was also a lot of paperwork involved and cracking down on cheaters would focus attention on the department.