People who always late , what is their deal ?

We organize CNY Open House at 630pm, We begin dinner at 7pm. At 9pm we clear the food because table gonna be use for board game. Guest come at 10pm, complain we didn't serve them food.

We organize trip, suppose to meet at 9am at certain place as we car pool to destination. Someone until 10am haven't reached. We are forced to go as we need to check in hotel before certain hour. That someone arrived only at 1030 and make a scene and demand refund from trip.

*Edit : Such people usually never update host they will be late or encountered unforeseen events like Accident, etc. Causing host to keep wondering about their status and can't prepare for it (e.g. keep some food for them).

I've met these people and usually they are repeat offended and never change.