I've noticed over the years that manners are almost a thing of the past.
The building I work in is shared with various other businesses so we all share an entrance to the building.
It's always quite busy with people coming and going, so nine times out of ten you will end up holding the door open for someone else who is arriving/leaving. No problem.
And this is no exaggeration.... for every 10 times I hold the door open for someone only about 2-3 people say "thanks".
I've gone from sarcastically saying "You're welcome".... which over time progressed into calling them "w*nker" under my breath..... which has now evolved into calling them "W*NKER" out loud!!
It drives me MAD. So much so that I now frequently go out of my way not to hold the door open for anyone in the building.
People just don't have manners anymore!
AND there's an ASN equivalent also:
Someone sends you a PM asking for info/advice... you respond with the info/advice they need.... and you receive no reply thanking you for your help.