Not entirely true.
I agree that the government relies on the motorists to pay for the benefit sysetm. But there is still a lot of oil in the north sea alone. There is also a huge amount of Black gold around russia CIS, Kazakhstan, azeri, not to mention up north around the arctic circle.
According to a major oil company i worked for last year there is as much oil in the north sea now as they thought they had back in the 70`s. Granted, its not as easy to get out as there is less pressure down there now. but there are ways to raise the pressure and make the baby gush
There is not a shortage of oil, at the moment most platforms run at about 50-70% capacity. Why create an excess of oil when you can keep the price of oil high by keeping it a supply and demand situation