Do you know who provides the odds to sportsbook? It's odd providers. There are not many odd providers considering the number of sportsbook exists. Many sportsbook have common odd providers and those odd providers store all information of the gamblers who gamble in their clients platforms. Not all are speculation as you think.
Genius, they also have the same odds. How are you supposed to arbitrage bet on Roobet and BC.Game, if they have same odds?