Presumably, for such a complaint, the cops wouldn't even bother to come to laugh at you unless they were very very bored. This is probably true in both circumstances you described. Also, I can't speak for others, but unless detained I wouldn't stick around most public locations long enough for someone to complain about a notification from my phone. Even if a call is received and must be answered, it seems appropriate to accept the call and leave the immediate shared area if possible. Obviously, in such circumstances as a moving bus, quickly leaving isn't really feasible.

However, I partially agree with the person to whom you responded. Your phone shouldn't make any media based sound (videos, music) in public. I also mostly agree with what I think you're saying: in most circumstances, notification sounds are inoffensive. Movies are not the only exception to this but definitely are one. Laughing in the face of someone who requests quiet in a public shared area seems rude, though, and might escalate the situation.

To elaborate, recently I went to see a dental surgeon. As I approached the waiting area, my immediate thought was to set my phone to vibrate. Once I entered, however, I realized that not only was there a TV in the space; also there was an elderly couple watching TV on their phones. Not only were they doing so, not only were they watching something different from what was on the TV, not only were they watching their media at BLARING volume, but they were also watching vastly different content. In this circumstance, notifications could be - reluctantly - forgiven, but their blasting and conflicting media made it very difficult to concentrate on filling out my paperwork.

I'm too much of a wimp to have approached them, but in that circumstance I think it would have been appropriate to ask them to silence their media and would have only required a vague awareness of the existence of others for them to have done so without prompting.

Though the cops, if they came, would likely still have just laughed.

An aside: as soon as the presumed wife left the waiting area, the likely husband shut off his media. I don't know what that means, but wanted to mention it.