By this logic, every dollar abroad should be worth only 50 cent in the price of a share - after all, that's the real value of that cash after all taxes (contrasted to the accounting value of the dollars on the companies' annual report).
You're right that it's probably discounted somehow by some investors, but it's also worth it's full value if they choose to spend it abroad, so it's not necessarily worth exactly what it would be worth if they repatriated it and paid it out as dividends. The discount depends on what the shareholders think will happen to the money, and I don't think anyone is predicting repatriation any time soon.
