Why should traveling jobs pay for their employees meals?

How is it any different than a job where you don't get to travel?

We don't reimburse our employees for the lunches/dinners they get daily for working for us.

Meal reimbursement as a benefit seems pretty messy given the variables involved in deciding how much to reimburse a person and how large of a reimbursement to give them.

I understand reimbursing the employee for plane tickets and hotel rooms because it's part of the cost of traveling, but a person eating isn't doing anything he wouldn't normally be doing.

Then again none of my employees or I get to travel for work, but I'll be miffed if we start paying our employees lunch expenses.