why do sportsbooks have different rules for the same bet at different books?

It seriously confuses me how you can bet on, say, "first to score" or player props at two different places and each book will have their own rules for grading, voids, stat corrections, you name it. One book will rule a push if the guy sits the whole second half, while another will say action as long as they played a snap. Had one with soccer too, where extra time goals counted at one shop and didn’t at another. If you’re hedging or trying to lock some arbitrage, the rules are half the battle, not the odds.

I get it’s in their fine print but it feels like you have to be a lawyer with a spreadsheet and a magnifier to keep it all straight. Just burnt by this on an NBA rebound prop where I thought both bets were in sync, but nope, voided at one, paid at the other. Anyone else keeping some absurd tracking spreadsheet just for the rules? I feel like I spend more energy micro-optimizing for the weirdest stuff than I do on the bets themselves sometimes.