As a retired teacher, I fully approve of Attendence officers or whatever they call themselves these days checking up.
In most countries, a doctor's note is required if children are off school for more than a length of time that varies from three days to a week.
In this case, it does sound, however, as if there has been a failure of communication between school and attendence officers, as the parents of the sick child had been in regular communication with the school.
That said, I would much rather that schools enquire unnecessarily than that they do nothing and later discover that a child has been playing truant, as a 14 year old girl I taught regularly did on Wednesdays until I phoned her father. He was shocked to hear that his dear daughter had not been at school and swiftly put paid to her window-shopping Wednesdays.
Worse was the case of the Pakistani girl who never returned to school, or even to this country, after a summer holiday. We never found out what had happened to her.
A 17 year old boy and his entire family likewise disappeared without trace, owing the school a term's fees, and we never found out where they had gone either.
There are so many tragic cases of abused, murdered children or youngsters forced into marriages they do not themselves desire (although this last is rare compared to the abused children) as well as those playing truant, some of whom get into criminal company, that I say: better safe than sorry!