Well, yes and no. Luck materials indeed don't drop at all from common drops. But, a random material isn't rolled. Rather a random tool is rolled from a list, with certain materials having a chance. Here's the common tool list for ultimate episode 1:
As you can see, TP materials also never drop, even though they are a regular green box. But that's because they have 0% chance. However, what you said is really interesting, because with psobb, the server is 100% in charge of the drops. In the end, common drops and rare drops use the same packet to let the client know an item dropped. And I knew for a fact the server doesn't check redbox flag, so it had to be something else. So I dug through the code to eventually find this:
Basically this means "if the tool number is 23, the rate is 0". Now if you start counting this table and start with 0, number 23 is luck materials. With that code disabled, and the luck material rate cranked up, luck materials drop just fine, even from boxes.
This change will be included with the next Destiny update. From then on luck materials will drop everywhere according to sega rates.