Been ordering parts from the us for 15 years now IMO its because pricing still hasn't adjusted for our dollar being strong now vs the u.s. now and for the last several years. If you owned a shoppe here why not gouge your customers more?
Remember though that larger heavier parts will cost more in brokerage /shipping etc especially through ups. If you buy rtabs and stuff insist USPS only if you can. You will still get charged tax duty and brokerage on rtabs but the difference is crazy still.