In general, I see a rudeness has overtaken much of society where I live as well. My hubby is one of those who will offer assistance if he feels it is appropriate (he is a car guy so knows all about such quick fixes...we have a big truck and occasionally he will offer to pull someone out of the snow, like if he sees its an older person or a stranded gal with kiddos...etc..such things are very hard on a persons vehicle, but he sorta does the "what would I want others to do for my wife, Gramma, etc theory, as you said).
I will do what I can as well, such as offer assistance to older persons in the grocery store with high shelves or heavy objects..its what I can do to help. But so often see others pass right by these opportunities to do a simple little thing for a few seconds to really help another out.
Its sad, but I see it all the time. Good for you guys for offering...poo for her for being rude.