Sometimes being discriminate is not at all about bigotry.
As for Senior discounts you mention, retirees are the most wealthy demographic segment in society. The kids are grown, the house is paid off and they don’t just give the discounts to the ones on fixed incomes, the retired doctors, attorneys and millionaires get them too. If it were a welfare program for poor seniors, that may have some merit, but it isn’t so it’s extremely discriminatory.
As for your comments that kids have no income, heheh, that is a pretty lame excuse. If the parents can’t afford them they shouldn’t have them and they certainly shouldn’t expect others to pay higher prices (which is what they do) to subsidize their food, housing and entertainment, which they also do.
Regarding the “favor” to parents, see my first sentence. You can’t excuse bigotry or discrimination by claiming “I’m not against someone, I’m just FOR someone else”. If the result is that another individual is unfairly treated in terms of price, service or goods and the determining factor is a state and federally protected characteristic like race, religion OR AGE, it’s discrimination and it should be illegal.