Meanwhile you’re probably paying for parking, gas, etc.
Also grand jury duty can be something like six months (may not be every day depending on jurisdiction. Federal may be even longer. Probably no company will keep paying you for that length of time even if you squeeze in some work nights and weekends.
The company doesn't get the choice. If they fire you or cut your pay over jury service, or even just threaten to to do so, and you can prove it, they can be arrested immediately. I have personally witnessed a judge issue a bench warrant for the arrest of a retail manager who told an employee that if she failed to get out of jury duty before her shift started that she would be fired. When the manager was brought in and questioned by the judge he tried to argue that it was his right to deny jury service by his employees. He was given 90 days in jail for contempt of court.