People need to understand boundaries

So I went to a brewery yesterday to celebrate a small achievement with my buddy. And as soon as we entered he grabbed attention. My husband was walking him from inside to outside seating tables and I was behind him. Suddenly I see a guy running towards my GSD saying he wants to pet him. I came in between two of them and blocked him to say sorry you cant run into him like that and resisted to pet. This guy is intoxicated I don’t know how many drinks he had and he didn’t budge. He tried to bypass me and come near my dog. My husband wasn’t aware of the situation at that moment so he said let him sniff you and if he is okay you can pet him. So he gets full on kisses from my dog and I look rude. Ok now we sat down and I let him know what happened. This guy started coming from behind and tried to pet him again twice without our knowledge as he became overconfident. My dog just lost it and barked at him furiously and next thing I see him is running away. I didn’t ask him to be quite as he needed this lesson but everyone was looking at my dog like he did something wrong. Why do people don’t understand the boundaries? Similar incident happened to us while we were travelling and the person threatened to kill our dog when we didn’t let him forcefully pet him while he was sitting in our car. Why people act like an a hole sometimes