Actually we probably would. But wal-mart founders would only be multi-millionnaires instead of bilionnaires.

Because I log 100% of the hands I play, and so do every pro/semi-pro players. It's then trivial to perform statistical analysis (the softwares logging the hands are made precisely for that). With thousands of players doing this, it doesn't take long until we know something is up. Most cheaters get caught. Or they aren't cheating good enough to affect our bottom line.