Most Ubuntu users don't know that Canonical only supports the main repository for free. To my knowledge, only some comments hidden in /etc/apt/sources.list men

Most Ubuntu users don't know that Canonical only supports the main repository for free. To my knowledge, only some comments hidden in /etc/apt/sources.list mention this, but the more honest approach would be to warn all users when they try to `apt install foo` some package from universe/multiverse. Or do it like RHEL with their EPEL repo and disable it by default. But I guess they would have never gotten this popular if people saw that Ubuntu is only a few thousand packages compared to Debian's tens of thousands.