Why does table shows other values despites having segment at hit level?

When you create a segment, whether it's hit/visit/visitor, it brings in everything that happens at that level as long as the conditions of the segment are met. In your example, you have a segment where sub-class = "laptops". So it is going to look at everything that happens in the hits where sub-class is laptops. In your cart abandon, it will show you the amount of cart abandons for laptops, but it will also show you what other sub-classes were were abandoned at the same time (in the same hit). 

If you want it to be just that sub-class only, don't use a segment, bring in the dimension and drop it in the table. You can put it above/below the metric 'cart abandonment' so it says "filter by" and then it uses it as a dimension and not a segment. On the left hand components menu click the little ">" icon at the right to dive into the dimension items, and just drag in laptop into the table.