From what a quick google search told me, RHEL caps out at 13 years.[0] I'm curious what caused Canonical to offer 2 more years of lts support than Red Hat?
So now, what do they do? Spend thousands of hours upgrading the soon-to-be-replaced fleet anyway, or ask their vendor if they could, pretty please, extend LTS for another two years?
If Ubuntu can spread the cost between enough (or large enough) customers, why not?