Actually, it’s not that huge a problem, although it does raise the cost of the project. A small pump set inside a sump neatly takes care of the problem. Water flows by gravity from the drains to the sump; when it’s full, a float switch activates the pump and it pushes the water out to the street. Water in the street can’t back up into the pump’s pipe because there is a one-way check valve ensuring that it can only move in one direction: toward the street.
This was one case where we could not create a space for rainwater to filter into the soil, since there was already a history of standing water at the entry to the garage. This solution, however, should eliminate the water, except in the case of a large storm coupled with a long power outage. In any case, water in the curb is now prevented from running backwards through the pipe and flooding the courtyard – so things are better than they were.