Compensate is the keyword. If you are not making that in your job you will not get that while serving jury duty, I believe.
Well, conceptually, jury duty is a civic responsibility. Not something for which you're entitled to compensation. The purpose of the reimbursement is to prevent making doing your civic duty so burdensome that a jury can't be seated because every potential juror would be excused on economic hardship grounds, and because justice would not be served if the jurors would be compelled by economic considerations to get out of there asap. jmo
Eta: I think I may have misunderstood your point. Yes, I think they would only receive that which they had to forego. Still a much better deal than $12/day, though!