OvertheUnicorn,
I think that within the totality of the HE community there is both a lower possibility and a higher possibility of neglect (or other forms of harm, including emotional abuse), depending on the family and the reasons behind HE.
There are very many who HE very well, for the best of reasons, and with extremely good regard to all their children's welfare. These are the HEers you know, and would fall (generally) under the 'low probability of neglect' - though tbh what goes on behind gleaming facades can be unexpected)
There are others who may HE unwillingly, for example after the appalling practice of some - often older - children being 'off rolled' by schools due to effect on results or SEN. These are sometimes children who are anyway disaffected and at risk of exploitation and abuse (e.g. through recruitment into county lines etc).
There are families who HE for cultural / religious reasons (for example GRT = Gypsy Roma Traveller, groups where girls in particular - depending on the specific family or group - are often removed from school at a young age). It may also include some more extreme or isolated sects, where the treatment of children does not always conform to what would be seen as 'the norm' for safeguarding in the wider society.
There are also some families who deliberately cut themselves off from all forms of authority, including healthcare and education, as it is seen to be interference from the state. Lack of access to standard medical, dental etc treatment, and the often very isolated nature of such families, might make some forms of neglect somewhat more likely.