That's for automatized crypto to crypto transactions, they all use whitebit, okx, binance, etc. and those cex are doing aml check and can block︀ transaction, when you send your crypto to exchanger from bestchange, you actually send it to︁ cex(in 99% cases), most of exchangers does not have their own liquidity, they use cex︂ for that. Basically you are paying % to them for exchanging your crypto on cex,︃ there is not much reason doing it, as they also put all risks on you.︄
Cash transactions/invoice payments is different story. They still sometimes will do AML check on crypto(before︅ you do transaction), but they never ask for any KYC, they will just tell that︆ they cannot accept your crypto if it will have too high AML risk or will︇ offer you to take it, but with higher %.
And again, most of bestchange exchangers︈ are in lowest part of middleman chain. It's better to look for direct contacts(in case︉ of cash/invoice transactions), you will have better % and no middleman.