"Our new macro detection system monitors activity on our servers and detects suspicious behaviour. This evidence is reviewed by our team of experts who either confirm or reject the system's analysis. Jagex will not reveal the exact mechanics of how this system works because this would make circumvention easier. " http://www.runescape.com/kbase/viewarticle.ws?article_id=2077#macro
Nobody except Jagex know for sure, but I do know you do not have to be reported to get banned for botting, although this could happen. They have programs in place to detect botting paterns, which then are reviewed by jagex staff and a decision is made about your account.
The thing with botting is to try to make it look as human as possible. Don't bot more then you would play runescape a day. Essentially, try to bot as little a day, with breaks if possible. This will lower your chances of getting banned greatly, whilst you still can enjoy the freedom of doing more important things while the bot does all the work.