That seems counter rational to me. Usually, you get better sell prices because of the increased risk of the method of payment -- more chargeback risk and less stringent AML/KYC procedures like Paypal, for example. At least in my case, at places I use to sell where I have to comply with AML/KYC, the tradeoff is slightly better prices and more convenience.
Yes I agree method of payment matters here. Probably a lot of US payment methods have higher risk of chargeback (for example paypal). Thus people selling btc in US are asking for higher prices to compensate chargeback risk. I will probably try to do some analysis on cash payment price: cash payment btc price in US vs in other countries. Not sure how many data points are available though.
That's what I mean. In my locations, we have other online methods of payments, not as risky as Paypal for chargebacks but the money's a little harder to withdraw and you need KYC (mobile money app) so the price is also a bit higher. So that logic makes sense. You get better prices because of the inconvenience and risk.