My family are often late for social occasions, meet ups and so on, usually by 20 minutes or so. They will always text to say so and will apologise. They lead busy lives and emergencies happen. I've learned to accept it but I like to be on time myself. I know people find it rude to be late.
However, my in laws are often early. They live some distance away (a 90 minute - 2 hour drive) so we invite them down to stay every few months or so. Last week, we arranged that they would arrive here for 1pm. It was my day off, DH at work, so I had time to sort DD out, do a clean, walk the dog, make myself look presentable, prepare food and so on before their arrival.
But they turned up at 10.20 meaning that the house was half clean, I was a straggly mess and not prepared to host their visit! DD is only 9 months old so getting everything together isn't as easy as it used to be and every minute is precious!
People really get wound up by lateness but it's often unavoidable. But you've got to PLAN to be so early. Isn't this even more rude? DH says its just how they are.
Btw - they were once 5 hours early in a similar fashion.