Jokes on you. Merchants prefer credit cards because there is less loss than cash. 2.5% is nothing compared to 5-10% loss at the register. Plus easier and more accurate accounting.
>5-10% loss at the register
Where did you get this number from?
90% of cash I give to restaurants goes in the pocket, not the register.
Bad service = card always.
If your employees are stealing you should probably nip that in the bud...
If you're expecting 10% loss at the register and have terrible service, that's a 1-2 punch for bankruptcy.