FreeBSD grep is just GNU grep, it appears, up to but not including 9.0. Note the long --recursive option in the manual page snippet that you posted; no properly God-fearing BSD program would support long options.
The new non-GNU grep in FreeBSD 9 was designed to be compatible with GNU grep (pedantically, with GNU grep configured with --disable-perl-regexp as it has been in previous FreeBSD releases) because lots of ports depend on GNU grep behavior. The fear of God is not a sufficient reason to break ports.
