Ofcourse because Simon (Hazard) created LVDM for himself, not for anyone else. littlewhitey helped on the gamemode and they decided to use that gamemode (LVDM) for littlewhitey's server. Simple as that.
As dominator said, FuseZ isn't really that good, so you script would be full of rendundant, memory gabbing code which would make gameplay laggy, and which won't attract players.
Clanservers are mostly edits from released gamemodes, or simple gamemodes made from scratch. Clanserver gamemodes don't have the purpose to attract alot of players, so it doesn't always have the safest anticheat or the most dynamic systems. Joker's server was made by TuneFish afaik, SAE's is an edit of MOB's gamemode (I think), an V's was made by Nado (not sure). Made by people from the clan for the clan, which they didn't get paid for. If you really want someone to make you what you want than you'll have to pay.
And since you're paying, I'd suggest you plan out a decent scheme and look for good scripters, which will cost u much less. If you want a professional devteam or a decent scripter you'll have to do some work yourself, you'll have to provide a SVN repository, set up an FTP server, get forums, pay for decent server hosting, or get a VPS, and get a decent administration team.
Going like: "hey I pay you, make me a gamemode", won't work, unless with ppl like Fusze I guess.
