Here is the rule in Washington State. The link also takes you to a site with more questions & answers.
8. May an employee waive the meal period?
Employees may choose to waive the meal period requirements. The regulation states employees "shall be allowed," and "no employee shall be required to work more than five hours without a meal period." The department interprets this to mean than an employer may not require more than five consecutive hours of work and must allow a 30-minute meal period when employees work five hours or longer.
If an employee wishes to waive that meal period, the employer may agree to it. The employee may at any time request the meal period. While it is not required, the department recommends obtaining a written request from the employee(s) who chooses to waive the meal period.
If, at some later date, the employee(s) wishes to receive a meal period, any agreement would no longer be in effect. Employees must still receive a rest period of at least ten minutes for each four hours of work.
An employer can refuse to allow the employee to waive the meal period and require that an employee take a meal period.
Breaks & Meal Periods
So while a meal period is required by law, it also allows the company to allow you to waive your lunch. They choose not to. Instead, they use it as just one more obstacle to work around. Anyone that does a long distance route that doesn't leave the barn until 10 or later knows what a impediment it can be. I don't understand the company's refusal to budge on this. It's perfectly legal to allow us to waive our lunches. They can't be sued for not giving us a lunch break. (Unless they think their dispatchers will use it to force drivers not to take their lunches. But a quick call the HR should fix that....)
It's just like our tractors shutting down. I burn more fuel keeping it running than I would normally use just letting it idle.