It's not a scam. It's the result of the difference on the trading activity of both exchange. You will notice that there is a big difference on the volume of token that being trade on both exchange. Considering that both exchange don't do wash trading.
Then it means that other user set Buy/Sell order higher/lower compared to the other one which result to the variance on the price. This happened a lot on the token/coin that has low trading volume and listed to a DEX or Exchange that don't do wash trading.
Thanks guys, but I wonder way buyers don't buy at lower price when they see lower price on other exchanges?
Because of liquidity. As you can see. If a guy bought cheaper on exchange A and sell to exchange B. Then you will notice that there is no buy order that can complete his order, only sell order is higher.
You must consider the withdrawal fee too on exchange. Sometimes the withdrawal is higher compare to the difference in price considering the volume of the token that you will trade.