Translation:Excuse me, is this bus leaving from Cairo?
If it is "This bus," you are probably looking at it. Why would you ever ask what city a bus that you were looking at was leaving from? You might ask "is this bus ARRIVING from Cairo, or COMING from Cairo." You are twisting up our brains with these nonsensical, illogical sentences.
You could be at the ticket office, talking to the clerk. Maybe you are in Luxor. And thinking, if this bus is starting from Cairo, it will already be full by the time it gets here. I better find a bus that is leaving from here, from Luxor. Then I can board a clean, empty bus. Also, if the bus is coming from a long distance, there may be delays before it gets here.
Or maybe you are in Cairo and want to make sure it is not coming from somewhere else, already full of passengers.
That is a perfectly plausible situation in Hungary, except for the settlements.
As for leaving vs coming, mixing the two is not a big deal in Hungarian. By using "indul", you are more specifically asking about the initial departure station.
So, it is probably just a translation issue.
Oh but of course we have the explanation for that. :) You have already bought your ticket, you stepped away from the counter, the clerk is already talking to the next customer. And then you remember to ask your question, step back to the counter and.... well, you know the rest. :)
But you can also just be overly polite, fully aware of the stress your ... questions are causing the poor clerk.
It could make sense, if i collect informations for a bus trip. For example: My friend lives in A (cairo), i live in B and we want to travel together to C in the same bus. I could ask, if the bus, which i found out, starts at A. But I don't know, why we are given such difficult sentences, which can hardly be understood. They sound sometimes like a proof, that nobody is able to lesen or understand Hungarian.
I think the present tense confuses.
Was this bus leaving from Cairo? or
Did this bus depart from Cairo? would make sense.
Or: Is this the bus from Cairo?
Is this bus leaving/departing from here? would alter the meaning but present tense and this bus, means here and not from where it originally left.
And this is throughout the entire course a problem that was not well handled.