I think basically it comes down to being, POLITE - KIND - THOUGHTFUL ...
Or for those who seem morally - ethically challenged:
ASK PERMISSION ... is that really "Rocket Science"?
Yes, they are there - but it would still be NICE - KIND and THOUGHTFUL and POLITE to ask simple permission????
Who knows what other treasures you might find from that person, because you took the time to ASK PERMISSION.
But than, I grew up in a different Generation.