Unix when it was released was made for business and was incredibly expensive, its
minix, and later
bsd-variants that made this free.
lastmiles: Solaris is a AT&T System V Release 4 based port of UNIX to a commercial implementation with full SUSv2 and SUSv3 spec compliance. Therefor its a good test bed for software compliance.
See Second-System Effect - trying to create better systems but spending forever adding all the features you want and never releasing anything.