Are money-changers offering better rates than interbank mid-market?

I guess it depends. For the consumer, it's luck. For money changers, it's their buy price for that currency.

Mid-market rate as shown on Google are just for reference. That is not the price banks or money changers get.

That would be the asking price of the other seller that is selling the money to the bank/money changer.

If by chance, they have currencies that they purchased cheap, then to lure business, they may provide better rates for you.

But do note, banks and money changers have cost. And all these will eat into their margins, deducting from the mid-market rate.

Hence, if you get rates better than what you see on Google, thank your lucky stars. (Maybe can shun bian buy 4D, before the luck runs out.)