Well, it's all about lucky.
Also I guess JaGex has a bot program which catches bots.
On summer I was botting, and I've botted like 15 hours+ and got banned. However, I was watching the screen at the same time when I got banned, there wasn't a JaGex Mod.
I've been botted on this week like 50-70 hours like 12-20 h in day, and got not banned yet.
It's about luck, also when you get banned on first time on your account that first ban is just a "warning" and you get banned just for 48 hours. And second ban is perm banned I guess.
Anyway, hopefully you get unbanned! Good luck