CentOS is arguably the most deployed server distribution of Linux, and it (RH) ships a perfectly fine python3 via SCL. Ubuntu is a snapshot of Debian unstable,

CentOS is arguably the most deployed server distribution of Linux, and it (RH) ships a perfectly fine python3 via SCL. Ubuntu is a snapshot of Debian unstable, and it's not surprising that shipping cutting edge packages results in a few that are broken.