Re: creepy encounters with cashiers
It's not an unreasnable expectation for you to give another human your full attention when they are providing you with a service. Be it in a shop, bank, restaurant etc...
It's simply good manners. If you must take a phone call/make one whilst you are at the point of service, 99% most of the times a simple "Exucse me but I have to take this call" or something similar will suffice. It shows you are acknowledging the person in front of you not ignoring them.
On the continent of wild endeavour in the mountains of solace and solitude there stood the citadel of the time lords, the oldest and most mighty race in the universe looking down on the galaxies below sworn never to interfere only to watch.