Price calculator doesn't respect quantity without adjustments

I created a simple field formatter for order items to display prices without tax, but including promotion.
For this task, I used the commerce_order.price_calculator service, which passes the given PurchasableEntityInterface through the chainPriceResolver and then returns
the calculated price by creating an order item and applying the given parameters on that instance.
If you take a look at the code of \Drupal\commerce_order\PriceCalculator::calculate, the
quantity is only regarded when there are $adjustment_types or $processors provided.
In my case, there were no processors found when iterating through $adjustment_types, but I
believe this is the same case, when an empty array (default value) is passed as a fourth argument.

Another great example is a helper service to provide consistent price calculation through the site.
I had to write an extra check because the 'promotion' adjustment type did not have a processor, and the
quantity was not regarded when the service returned the 'calculated price'.
(The second method, calculateTotalPrice() always returned the correct amount.)

  public function calculateNetPrice(PurchasableEntityInterface $purchasableEntity, $quantity = 1): Price {
    $priceCalculatorResult = $this->priceCalculator->calculate($purchasableEntity, $quantity, $this->currentContext, ['promotion']);

    if ($priceCalculatorResult->getBasePrice() === $priceCalculatorResult->getCalculatedPrice() && $quantity > 1) {
      return $priceCalculatorResult->getBasePrice()->multiply($quantity);
    }

    return $priceCalculatorResult->getCalculatedPrice();
  }


  public function calculateTotalPrice(PurchasableEntityInterface $purchasableEntity, $quantity = 1): Price {
    $priceCalculatorResult = $this->priceCalculator->calculate($purchasableEntity, $quantity, $this->currentContext, ['tax', 'promotion']);
    // ...