My husband feels its disrespectful when she just expects us to do things like mow the lawn or shovel. It could be because he is a SAHP and his family seems to think that he has all the time in the world to do whatever they need. In reality, he has three kids under six to manage and it's not an easy task. That bit about borrowing the car without much communication would never fly in this family! In fact, I don't even know if she would let us borrow it unless we had some dire reason. Which I guess goes to show exactly what the family situation is like.
Some of this is just cultural, as discussed already.
Some of this is just being "squeezed", in the sandwich generation.
I remember when my grandmother died...she was 65. My grandfather was 69-ish. There is no way that man would be able to fully take care of himself. Not that I think 69 is old (he lived to be 86), he just was not a man who was going to be able to care for his full house, feed himself, etc. My mother and her sisters would go to his house to help out. I remember an entire summer going 3x a week with my mom (I was 11 or 12), to clean his house, prepare him some food to reheat, visit, etc. My grandpa was an awesome guy.
But here's the thing. I was 11. I wasn't 2 or 3. It was the summer. My mother did not work (yet). Her children were 17, 11, and 9. She had time to do this. My aunts were both working, but they helped out, (they did less). My grandfather remarried the following summer.
I could absolutely, positively, not do anything like this. I do not live near family, but if I did? My stepfather went through a couple of years of cancer treatment in his late 60s, early 70s, when my kids were 6 and 12. I have a full time job. I literally do not have time for everything that I already have to do - there's no way I could be taking time off to mow his lawn, clean his house, or cook him meals. (I did change a trip to drive in for 4 days straight and do just that, right before his cancer diagnosis. He was THRILLED but he would never expect it). Luckily, his brother and sister are nearby and retired, so they were able to drive him for his treatment. He's learned to heat up food. For awhile he was able to have a cleaning person, but she got a ft job. My sister and her husband and son help out a LOT around the property - but again, my sister's son is a grown man. She works FT, her husband works, but they aren't managing children in schools.
It's a completely different dynamic when you have small children and/ or a full time job on top of that.
Like it or not, as people have aged and live longer, and as people put off having children - you are going to see more and more of this. No longer do you have a 70 year old mother with a 48 year old son and 18 and 24 year old grandchildren. I mean, you do, occasionally, but not as often. My inlaws/parents are between the ages of 72 and 82 and our kids are 7 and 14 AND we both work full time.