Well, it may be cheaper for some, but, in general, sellers must be charging more than what they're buying for, otherwise, their business is not sustainable.
Yes, business wise, you need to do that even just a little profit you can gain.
From the seller's perspective, does it actually matter if a buyer is highly rated or not? Are buyers actually rated as well?
I don't think it matter since the buyer will need to send first the fiat. The seller will only confirm if he receives the fiat then release the crypto afterwards.
What should be avoided is those order who has more than 15 mins. time and fiat payment method such paypal or other transaction that can be reverse back
What concerns me is:
To my understanding, Binance is locking the crypto to make sure the buyer receives it. But is there any similar security feature for sellers? If buyers are sending fiat directly to sellers, what happens when the buyer says he has sent the payment but the seller didn't receive anything? I'm guessing Binance would require some sort of proof from the buyer that he indeed sent the money - but what would that proof be? A screenshot? That can be easily faked. Or are fiat transactions also going via Binance? What am I missing here?
Seller should report it and open a dispute, give every details as much as it should be. And let binance decide the outcome.
To be honest this is always be the case in every platform when it comes to p2p, there are also existing issue other users experienced.
That is why dealing only to higher rated or verified seller or merchant or whatever they call it will lower the chance of facing this kind of issue but it won't give you 100% assurance so always proceed with risk.