This thread probably highlights what these threads always highlight: everyone's normal is different. Also, that we tend to invite people for dinner who are going to be on the same page in terms of social behaviour.
If we invite friends for dinner at 7.30, no one in my circle is going to turn up early (thank God), and they're very unlikely to be ringing the bell at 7.30 on the dot. They'll do the civilised thing and arrive at around 7.40 - 7.45 ish.
Likewise, they know I won't be hovering with filled plates to bang on the table at precisely 7.30. They'll be drinks, chat and a canapé or two. That way, if someone is running late, it's not a crisis. I'd never prepare food that needs split second timing with guests, because that would be too stressful.
No one needs telling these 'rules' - it's the unspoken way of things in a group of people who do things this way.
Other people's normal is not this! Half the thread will be horrified at not arriving early and not 'being fed' until an hour after arriving. No one is wrong, it's just different, and we all think our way is the right way 
I've yet to feel angry about someone arriving late to eat. Life is so bloody busy and if someone's late, there's usually a reason for it, and it just doesn't wind me up much. Most people are decent and not trying to take the piss, ime.