about the use of "can"

I'd have a really hard time explaining exactly why this is so, but I'd say that the sentence, "Can you let me have two tickets?" is one that would be used when you're asking a large favor of someone, like giving you the tickets for free, rather than paying for them. It also kind of humbles the person asking with res;pect to the person being asked. On the other hand, if you went to a box office to buy tickets, you'd be more likely to say, "Can I have two tickets, please."

Thank you so much for your quick reply.
I'm a green hand at this websites, and I come to love this place.

Can = ability
Can you get me tickets for the game?
Can I have them?

may = permission
May I have two tickets?

This is another prescription, Punkey, or in other words, it is an inaccurate "rule"/assessment of how the English language works.

'can' has many meanings, only one of which is 'ability'. It also holds the meaning 'possible', as does 'may'. In fact the deontic [deontic = social modal meaning] meaning of 'may' for permission came from the same epistemic meaning 'possible'. That's the same for might & could, .

All four, 'may/might/can/could' are used to ask permission.

Corpus studies have found that 'can' is used much much much more than 'may' to ask permission.

May/Can/Could/Might I have two tickets all = Is it possible for me to have two tickets?

The differences between them simply express varying levels of politeness.

I would even go so far as to say, without any proof at present mind you, that,

"Do you think I might be able to ... ."

would see as much use as a straight 'may' of permission.