Not quite true - a minority of agencies do have T&C's on the website, the majority do not....they want/prefer you to join their "database" before they give the info.
If you do find an agency with info the T&C's will be very similar for all - there may be some variable add ons with different agencies (LoL insurance, maybe training time Vs pay etc) but the basic T&C's should be pretty much same same.
There will be other agencies - and not recommending anyone - but both Longreach and CREW have T&C's on their webs that involves China, Korea and Japan.
Cheers all.