I think the only solution to feeling bad for a child or wishing a parent would spend more their child is to completely forget that the parents exist between 9 and 5
You've opened a business with operating hours, and they pay for services within those hours. What they do after that should not enter your mind, at least that's how I maintained my zen!
Each family raises their children differently, but that doesn't mean they love their children any less than the rest of us!
I have faced criticism on the opposite side, I work from home so I can have my children home with me FT until kindergarten. People think I'm doing a disservice by not exposing them to preschool, sending them to daycamps in the summer....blah blah blah.
I say do what makes you happy and tune the rest out, you'll enjoy your day more!!