I think it depends on the family. I’ve known how much my parents make since I was a teen I think.
How much my parents make doesn’t influence me at all in asking them for money or not. If they made very little I wouldn’t expect anything obviously. I don’t expect anything anyway, but what I mean is, let’s say they make a good salary, if they made $100k or $300k would have no effect on me thinking I should get money from them.
My husband would NEVER want to ask my parents for money. They do give us bits of gift money for birthday and Chanukah, and now that they are getting older the amounts have gone up, but for years it was a few hundred dollars, but if they had given us nothing it would be fine. We get nothing from his parents. We had and have zero expectations. I can’t imagine any man I know thinking a parent of his spouse/SO should be giving money to them. If you think that he will want it exoect money then I think it is best to not tell. We try not to give my husband’s family any idea of how much money we really have. I have no idea what they think.
That brings me to the point that how much money you make is very different from how much money you have. Having enough money for retirement is part of the equation. If you have a nice nest egg, that means your daughter won’t have to worry about spending money to care for you, which saves her money in the end.
If she has never asked I don’t see why she would suddenly ask now. Is there a reason you think she might? If she needs money I think she’s more likely to ask to borrow some money than ask your actual salary.
If you feel they are truly doing their best, and want to give them money when it’s very difficult, so they don’t get into a financial hole, because financial holes mean having to spend even more money than the original amount, then give your gift. I don’t think there’s anything wrong with that, but I wouldn’t make it a regular bail out of any sort. Although, it sounds to me like you don’t want to give them money. That’s fine too. It’s up to you.
Is she very young? Under 25?