Hi, D, and welcome to the G.E,
As if you haven't already spent your precious time being snarky? What a waste!
I think you have misunderstood what David means here. David wants to refer to the fact that "punctuation is crucial in written English" as it helps to clarify the writer's intended meaning and makes the reader able to understand it. Without proper punctuation, it would be very difficult to comprehend English. That's why, this site pays much attention to it.
which is more accurate people must wear masks or have to wear masks
I see that both are possible, but 'have to' would sound better if this were a question in an exam.
1. People must wear masks in public transport or they will be fined.
This is the voice of law itself or it might be said by a person in charge.
2. People have to wear masks in public transport or they will be fined.
This is what someone will use when informing someone else of a situation. He/She is just reporting what the law says and means that wearing masks is mandatory.