You have all kinds of confusions in saying that "All the BSDs are binary compatible with Linux." First of all, you pretend there's one binary format. Second of all, you pretend there's one Linux. Both are wrong. I can promise you that your Slackware x86 binary with x86 instructions and slackware admin and path stuff is completely useless to someone using BSD on a Sparc. There is a lot to think about: machine hardware, kernel syscalls, and normal admin bits. Some of those are sometimes compatible, some of them are not. My Sparc can run Solaris binaries under BSD, but only if they don't expect Solaris sysadmin crud. And then you have the whole problem of different Linux-derived operating systems. I have programs that work find under Redhat's OS but which fail miserably using SuSE's OS, even on the same hardware. Compatibility isn't all it's cracked up to be.