You’re absolutely right. Being late is rude & thoughtless & inconsiderate.
I used to be late all the time, until I took myself to task & with the help of August Birch (shout out here) started kicking that habit. I’m still battling that demon. But here’s what I tell people to do when waiting for others: use the college criteria. If the person you’re waiting for has a high school diploma, you wait for 10 minutes; a Bachelor’s degree guarantees a 15 minute wait; a Master’s gives you 20; a Ph.D is a 25 minute wait.
Me, on the other hand, while waiting for others, is a different story. I have at least one book & several journals that serve different functions, so I rather enjoy waiting & I never, ever take it personally. But that’s a personal choice.
But as for running late, my parents have raised me to know better than to have others wait on me & I am deeply ashamed when I make people wait.