School Safeguarding Lead here. It's not quite as simple as "this is neglect" or "it isn't neglect". There are a lot of variables and context is very important. One of the biggest challenges in safeguarding is making a distinction between a parent neglecting their child and parenting that is not ideal or in line with how I or my colleagues would personally parent our children. There are many things I would personally not wish for my children that do not come under the category of neglect or abuse.
At the school where I work Teachers will not release a child to walk home alone until Year 5. That is school policy. Once they are in Year 5 parents can send in written permission for them to walk/cycle home independently if they wish.
If someone came to me with a concern that a 10 year old child was going home to an empty house and would be there alone until their adult returned later in the evening I would speak to the parent, and the child to establish the following:
What time will the parent usually be home? If it's 5.30/6pm that's very different to it being so late into the evening that the child is unable to have dinner or go to bed at a reasonable time.
How does the child feel about being left alone? If they are distressed or worried by the situation that would be a concern.
Do they have access to a landline or mobile so they can seek help in the event of a problem?
Does the child understand what they would need to do in the event of an emergency and can they explain this confidently?
Has the child sustained any injury or harm as a result of being left unsupervised?
How far away from home does their parent work and are they contactable? If they're not able to get back quickly in the event of a problem I would expect them to have a neighbour/relative/family friend on 'standby' that the child could easily get in touch with.
This would also need to be considered in the context of the child's general presentation. Are they generally happy, well rested, clean and well turned out? Are they generally on time for school and is their homework being done? Rightly or wrongly, if the child is happy, seems to be progressing well and there were no other safeguarding concerns then I can guarantee that Children's Services would not be interested in a capable 10 year old being on their own for a couple of hours each afternoon after school.