We are like that, too.
Several of our customers are automotive and they want a full validation for even the slightest change.
A case in point. We had shortages of 0.1uF, 16V, X7R, 0603 MLCC. You know, the ones that you sprinkle on a board like salt and pepper. Our purchasing people told us that they had found a large cache of 25V caps from the same series from the same reputable vendor.
Well, the supplier quality engineer at our automotive customer wanted to perform all the validation tests, including EMI. Talking in excess of $25K and 8 weeks minimum.
So we had to procure from distributors, gray market components, and paying twice as much.