"Cardcounting" is technically legal, but frowned upon by casinos, because it violates the "unwritten law" that casinos are supposed to come out ahead. When card counters are caught, casinos can expel them under threat of being charged with trespassing.
But apparently casinos sometimes do more than that, like refusing to cash out their chips, or taking card counters to back rooms for questioning. (Detention and questioning are powers supposedly reserved for law enforcement. The casinos are only supposed to detain people until the police arrive.)
How do casinos manage to conduct such "extrajudicial" proceedings? Do the police and courts turn a blind eye to them because the casinos are important to the local economy?