Patents. To distribute the codec itself or content, you might have to pay patent fees.

For codecs, they are not flat fee[1], but per piece shipped. Which obviously, presents a problem for linux distributions. Even if they had money, they cannot count how many instances there are.

[1] Well, there is a ceiling, if you ship a insanely huge number of them. Linux isn't it. Cisco is, which is why we have openh264 binaries by them.