IIRC, the reason they have strange requests is so they know the crew actually went through the list and fulfilled all requests. Asking for only red M&M sounds silly but if you see a bowl of red M&Ms in your trailer, you know the crew was more likely to be diligent with the other requests. Those other requests being sound equipment and safty measures.
The point wasn't to have red M&Ms, though they taste good, it was a test to see how well the crew followed instructions.