Why is the final price of the product not available when I load it via Product Model?

I have a product which is affected by a catalog price rule and nothing else. The regular price is 14.99. The final price is 3.0

Now I want to export this product with the final price. I build a Plugin which is supposed to add the final price of the product.

    public function afterGetExportData(FirebearProduct $subject, array $result)
    {
        foreach ($result as $item) {
            /** @var MagentoCatalogModelProduct; $product */
            $product = $this->productFactory->create();

            $productId = $item['product_id'];
            $this->resourceModel->load($product, $productId, ['final_price']);

            $price = $product->getPriceInfo()->getPrice('final_price')->getValue();
            $result['final_price_export'] = $price;
        }

        return $result;
    }

But the expression $product->getPriceInfo()->getPrice('final_price')->getValue(); returns the regular price 14.99. Which is weird because in a different context (with a Collection) I get the correct final price:

    public function after_prepareEntityCollection(FirebearProduct $subject, MagentoCatalogModelResourceModelProductCollection $result, AbstractCollection $collection)
    {
        foreach ($result as $item) {
            $finalPrice = $item->getPriceInfo()->getPrice('final_price')->getValue();
            $item->setData('final_price_value', $finalPrice);
        }
        return $result;
    }

$finalPrice = 3.0
Why is the final price loaded in scenario B but not in scenario A? Both are working with the Product entities. But one is using a collection and the other is loading the Product entities separately.