They do, under the hood. (or did at one point.) the problem is it doesn't work. it's functional, but just doesn't give the level of performance needed at the top end (where wifi isn't a good enough connection).
They used to, a very long time ago, and when they did it was an outdated version. Nowadays they have a proprietary alternative that sucks.
Modern Samba is limited by the TCP stack. You can get 10gbps to work as long as your TCP stack is performant enough with very basic tuning on the server side. The client "just works".
macOS stopped shipping Samba with 10.7 Lion. Even before Samba was outdated.
