I think a lot of the problem is that there are some parents (note, I said some! Not all) who keep their children off for other reasons that aren't acceptable, or whose children have multiple days off ill when actually they would be well enough to be in school.
My son is 10, Y5, has had a cold this week. However, he is has not been ill with it. Eating me out of house and home as usual, playing happily, sleeping fine - aided by a bit of decongestant. So, he has been in school. Some parents literally keep their kids off at a slight sniffle.
Then you get the ones who keep kids off because it's their birthday/routine optician appointments- yes, as a teacher I have actually had a kid off all day for this reason!, to go shopping etc. Some kids attendance is poor and it does impact learning.
I know some kids get ill more than others but since starting school in reception, my son had 2 days in infants as he got food poisoning and was vomiting. He had one day off last year as he had a bad fever with a cold. Other than that, he is in.
As schools, we are judged, by Ofsted, on attendance and we are expected to show that we are doing everything we can to ensure children attend as often as possible.