force players to launch the client using silkroad.exe (non-bot trading)
changing the locale (though anyone with a hex editor can "bypass" this but it worked at some point)
aside from phbot having plugins (scripting) any random "DEVELOPER" could download supermickey or nexus change it to automatically answer these math questions and redirect the client to the local proxy
read my reply here

for an example of how to "bypass" these kind of systems by "extending bot features"