Ok, here it comes again..
Is this as in:
You cannot pay FOR me? (you pay FOR me, for my service) /ACC
You cannot pay TO me? (so you give the money TO me, ie for some product) /DAT
Is there a difference in these two situations in German? How would it be?
In my native language (Czech), there is. I'm just trying to get it.
Du kannst mich nicht bezahlen? = You cannot pay me? = You cannot pay for me? = Nemůžeš mě zaplatit? (CZ)
Du kannst mir nicht bezahlen? = You cannot pay to me? = Nemůžeš mi zaplatit?(CZ)
I think in EN/DE the logic is the same as in Czech: you will use Accusativ is the person is too expensive for you and Dative is you can allow to pay that person, but there is for example some technical problem (the bank is closed, you forget the account number, ...)
And yet in earlier lessons where we learned the verb bezahlen it was almost always translated in English as "to pay for." The sentences were in the travel section... I remember something like "Wir bezahlen den Mietwagen." It wouldn't make any sense to pay the rental car directly... You pay FOR the service... Unless maybe rental cars in Europe are coin-operated? Maybe the sentence was "Wir bezahlen die Reise." Either way, für was not in the sentence, and yet the English translation put it there... Which means it was implied by the verb... Which makes the original question here appropriate.
No, both are okay; the difference is in the emphasis. I'm not sure how to go into more detail...
"Hey, my company is going through a difficult time, and my bills are stacking up, and..." "[So] You can't pay me?" or "Are you saying you can't pay me?"
Whereas the other one would be more like a request out of the blue
"Can't (or can, both will work) you pay me those 50 bucks back?"
Well, we say both, but it depends on context.
If you and I went to a restaurant and I offered to pay for the whole bill, I would be "paying for you".
I might say to you, "It's ok, I will get this. I will pay for you".
On the other hand, if you were the waiter/waitress and I was paying the bill (handing you the money), I would be "paying you".
So to get the waiter/waitress' attention, so I can pay: "Excuse me Sir/Miss, may I pay you"
This sentence is a question. Then why Duo can simply make it Kannst du mich nicht bezahlen? I understand it is possible to say but they are usually strict about the grammar and then this? In English again it is possible to say You cannot pay me? but usually we say Can't you pay me? Or is it normal for German to say? It is a bit confusing to me. I hear people say Du kannst mich nicht bezahlen, oder? but without oder it looks not right. Opinion from native?
I understand your confusion. Look up "rhetorical question."
Also, imagine it in this scenario:
Person 1: your bill is $100. Person 2: I can not pay you. Person 1: You can not pay me? Person 2: no.
You might repeat a statement back as a question in order to verify it. The tone you use has a great effect, though, so doing this can sound angry ( "you crashed my car?!?") Or excited ( "you won a million dollars?!?")
Can't it be "jemandem bezahlen"?
wenn Sie mir 100 Euro bezahlen, verrate ich alles!