Can you just walk into a casino?
Can you just walk into a casino? Sure. As long as you are over 21 no one will stop you from just walking around, in fact you will likely appear to just be looking for a slot machine and taking your time about it. Sometimes, I purposely plot my route from restaurant to my room just so I can scope out any slots having a fun bonus.
How do casinos know how much you spend?
Thus, the operator has a detailed record of your gambling preferences. It knows precisely how much value you bring to the casino via this behavioral data tracking. If you play at multiple properties owned by the same company, they will also know how much money you have spent at each one and when you have visited them.