I'm finding it hard to follow you norah.
In your post of 15.58 you said I find that many people younger than 40 define courtesy, respect, and decency differently than you
Then at 17.40 you say Courtesy or manners haven't really changed by definition that much. It's rather confusing.
I'm not sure who your reference to 'that sort of niggling' was directed to, but if it was to me, my question wasn't intended as a niggle.
It was a genuine enquiry about how in your opinion, and those of the under 40's, respect and courtesy had changed.
Personally I think respect has to be earned, but courtesy is deserved.
Respect can of course be forfeited, but I think it's never wise to treat others without courtesy.