It may also come down to laptops being produced and sold mostly by US companies, which means that the general fact of most items (e.g. produce) being much more expensive in the US compared to, say, Europe doesn't really apply.
Sure, maybe. In the end, what makes an expense big or not is which proportion of their income goes towards it. Most of the rest of the world has (much) lower salaries, and as you pointed out, often higher cost for equipment. Therefore, the purchase is/feels larger.