I also belong to the notion that we are a family and as such we all work together and for the first few years my DS, then 14 and 15, babysat his sister 8 years younger, just because I needed or wanted him to, without any monetary reward. I have been a single parent since my son was 1 year old so there are many times (probably at least once a week) that he has to care for his sister. I have never thought about whether the care was necessary because of pleasure or because of work, just a necessity because why would I pay another teen to watch my daughter when her brother is right here? On the other hand, I try to plan my outings when he will be home, like school nights after she goes to bed or only one weekend night every few weeks.
So, yes, I said I never used to pay him but... About a year ago, my very precocious daughter decided she had issues with staying home with him (I know he was getting bossy with her too). I was getting phone calls from both of them two or three times each time I went out. So, yes, now I pay -- BUT I pay them both, $5 each, to not bug each other

. He is here to make sure nothing happens and in case of an emergency, but they are both responsible for making their own sandwiches, picking up their own messes, and completing whatever other chores I've asked of them. If she doesn't go to bed when she is supposed to, she loses her $5. If he gets his "king of the hill" attitude and throws her off the phone or something, he loses his $5. The money doesn't mean much to him as he works a part-time job anyways, but the system works for whatever reason.
As for leaving the 10 year old home alone, I only wish, She won't even stay on a different floor of the house without someone there. She follows me from room to room and we won't even get into our sleeping arrangements. She doesn't neccessarily need me, any other person or child will do. She is terrified of being alone and No, I have never left her alone or forgot her anywhere, she was born this way

My son started staying home for an hour or two after school at about age 8 1/2 and was staying home for a few hours by himself by age 12. I fear she may never stay home by herself.