This is a criticism.
Compare:
Requests
~ Could you lend me five pounds until tomorrow?
~ Do you think you could help me for a few minutes?
Orders and Suggestions
~ When you’ve finished the washing-up you can clean the kitchen. Then you could iron the clothes, if you like.
~ If you haven’t got anything to do you could sort out your photos.
Criticisms
~ You could ask before you borrow my car.
~ George could really do something around the house for a change.
The first one is correct, the second one isn't.
We can use both can and could to ask for permission. The difference between the two is in the more formal and polite use of could.
However, could is more natural in asking for permission than in giving it, so, when we want to give someone permission to do something, we use can.
Could I ask you something? - Yes, of course you can. (NOT ...of course you could.)
