It was supposed to be 1 warning, and it's because for some reason people don't have sound on or didn't hear you. I'll edit the rule rl quick
Are they having issues hearing others speak? or are they saying that they have their sound off? Sound should always be on while playing this game or you can be killed, RP or not, it's not very smart to have it off. Besides, if you see a guy walking next to you or following you for a bit with a gun, you should probably know what's going on. Fleeing from a robbery can get you shot. Then again, if you are sure they are trying to rob you before they're even close, you could always run away (not /home, or /tpa away). If they weren't going to rob you, they could always ask in world chat. But making us say it in world chat kinda sucks, but I guess if it's just one warning in chat, that's fine. But I've never heard anything about someone claiming to not hear voice chat, but can hear the rest of the game, that sounds like BS to me.
There is the flip side though. They could say that the person didn't say anything to them just to get rid of some bandits, or to get their stuff back. I've first hand tried to stop someone and they just kept walking away, they eventually seen there was 4 of us, and he said "hold on one sec" in voice chat, and moved a bit more before ALT+F4ing right before our eyes. His friend said "He's game crashed." Which seemed a bit fishy, because of the timing. We got Jayy over to us, we talked with Jayy, the guy logged back in and immediately /home'd right before all of our eyes. So that ALT+F4 was clear. Jayy seen this, and tp'd to the guy and gave him a stern talking to, and gave the guy a warning. But the guy clearly heard us, and he claimed he didn't. Then changed his tune and told Jayy that we were going to kill him. (we did give more than three warnings, and he just kept walking, technically, we were in our rights to do so, but we weren't going to do it as soon as he logged on.)