That is because you are doing it for free.
She may never have asked them either. People don't always realize what's needed if no one tells them.
How often do they come over?
Then by all means, they should do it. I thought you meant a once a month visit.
An old Chinese proverb says that when you do someone else's job they thank you for helping them. When you do the job again you don't get thanked because now its your job.
Mowing your neighbor's lawn and shoveling her walk is YOUR job. That's why the kids won't do it. To get them to do it, you first have to give the job back.
So you're a fool.
Up the top you said you're not complaining. Yet you are doing that too. If you aren't complaining what do you call it? Whingeing?
lazy little bums