I believe the thing about people preferring USD is not about the exchange rate itself but about the period where the rate is going up as their local currency tanks. For example a little more than 3 years ago our local currency tanked hard and during those 6 months people were rushing to exchanges to convert their fiat to anything else including Dollar, Euro, gold, etc. If you paid anybody in USD those days, they would have been more than happy to accept it and even give you a discount.
These days on the other hand, most people don't go for that trade since the exchange rate has been relatively fixed with some swings so the incentive is lower although it still exists.
That's basically like paying someone in bitcoin when price is going from $20k to $70k (they'll love it) compared to paying someone in bitcoin during these days when price is not going above $25k and sometimes even drops lower to $17k (they usually don't go for it).