Not only that, but kids notice it when you're not there, and they grow to resent you for it regardless of what your explanation for being gone is. This can either be a physical absence or an emotional absence.
When I was a kid, my dad went through a religious conversion. My mom, remaining a good Catholic, stayed with him regardless of his life choices. One morning in a fit of rage, she told an 8 year old me "if you go to church with him then I'm not your momma anymore."
Now, she didn't mean it. She has always been more loving and caring than I had any right to. But the words "I love you" were absent from her vocabulary. With an adult's perspective, I see that it's how my grandparents were in their personal relationships with their kids, too, although my grandmother had a great deal of warmth and love to express to us.
It wasn't until I was in a van with my sisters and my dad and we got into a roll over accident that I heard those words again from my mom. Covered from head to doe with bandaids and bandages and in my bed, she came by to comfort me and I shrank away. She asked me if I was alright, and if I needed her to stay with me that night, but then she asked "do you think I don't love you?"
To which I replied: "That's what you told me when I was sitting at the kitchen table getting ready for church." She had forgotten about the moment, because she was one who made ultimatums to kids whenever she had lost her patience. I never did. And so from 8 to 12, I spent my childhood believing that my dad was crazy and my mom didn't love me.
It matters. It affected my early childhood. I was a straight C student with a penchant for being incredibly disorganized and distracted. I also read over 400 books my 3rd grade year because it was my escape from reality.
Today, I know my mom would have done anything for me, but she had to she tell me that she loved me, first.