Because well, kids usually don't tend to cook for themselves so the parents end up cooking for them and eating with them.
That might be my bubble though, my friends / family have jobs that allow them to leave work around 5-ish and with school ending somewhere between 4-5, it's not that much after the kids are home. (or they pick up the kids after school).
If your income as a Google engineer is so tight that you have to make sure you get the most out of breakfast and dinner, go for it (but also maybe have a long hard think). The culture may well vary between sites, but this idea that Google (and others) exclusively employ fresh college grads and try to embrace then 24x7 just isn't true. We have families just like anyone else, and they matter to us every bit as much as everyone else's families matter to them.
I for my part am happy that I get a healthy, hot meal for lunch so dinner can be a quick snack when I get home, so I have more time with the kids. The alternative is more time spent on chores.
Please stop spreading these tired tropes.
I absolutely hate the "Whats for lunch today?" shuffle.
If you can eat faster, you get back to work faster. An early breakfast or tasty late dinner at work is a temptation to spend more time there.
I had a quick google and I’m not alone in my opinion. I’m not criticising the practice, it makes business sense and employees can choose not to use it.
(The other major driver behind food was supposedly the fact that the founders were PhD students and had found that some of their best ideas had arisen from informal discussions with other researchers over lunch, so they wanted to create an environment where employees had that same opportunity)
Seriously, if you're working somewhere where people care what time you go home, you can really do better!